I guess it depends on how much you each eat at meal, and what you eat/cook, and how often you serve it.

Okra depends on how often you want to eat it. You only get one or two okra pods per day off a thriving plant, so you will need to judge how many per person per serving, and how often. I have a bag in the freezer that I grab what I want even now in March.

One or two cherry tomato plants might be enough if the plants get big.

What do you want to do with the peppers? If you want to can or pickle then you can plant several, but if you want some to occasionally have one to cook with, then one or two plants will do.

BokChoi and chard you might take the whole plant and will will need to succession plant every two weeks - that's rows.How many depends how often you intend to eat these.

Snow peas could be many plants if you intend to freeze the extras. It takes quite a few to make a side dish for a meal.

How many leeks will once again depend on what you want to do with it: soup; braise; dehydrate for future use. If you only want the occasional pot of soup... that's one amount, but if you want the others, then many more.

It's hard to start out telling someone how much to grow. I know how much for me, but for you.... ????? I guess trial and error the first year will let you know what you plnated too little or too much.

Good luck!

Another thought: plant fragrant flowers among your vegetables so the bees will find the flowering ones veggies too.

Not much advice to give, in that yields can differ dramatically as a function of nutrients, water, sunlight, etc. It also depends on how long harvested vegetables last, but that bears on storage space. Most people just have enough friends who they can give stuff to! Food pantries are usually welcoming of garden harvests as well. As a result, it mainly depends on how much work you're willing to put in.

It sounds like you'll be growing in containers on an Apt deck/balcony? If so then cherry tomatoes and banana peppers should do well in a 5+ gal pot for each plant. Keep in mind that they will need almost daily watering as they grow large by late summer, esp the tomatoes. Herbs should do well too in containers but unsure of the rest. 6-8 hours of direct sun is best. My luck with past container crops has not been very good and production has been marginal for me.

How much space do you have to grow? Or what containers are you growing in? If you have limited space, it can requre a bit more planning and attention. But it can be done.

Only you can really say how many of each plant you need. Think about how much of that produce you currently use. Like leeks. Do you currently use one a week, a couple- a couple every couple weeks? Do you tend to eat swiss chard more often or bok choy- you might want a couple plants more of one or the other.

A little more info: 

We have an 8' × 4' patio, and I have 7 one gallon pots and 25 7 gallon smart pots for the bigger plants plus a few verticle pots that also hold roughly a gallon. 

We usually eat Okra once or twice a week at dinner.

Tomatoes I would say we eat on average 3 times per week.

The peppers I eat every single day.

Snow peas 2 or 3 times a week.

We would probably go through about 1 leek per week.

Swiss chard would be eaten every day.

Bok choy would be eaten about twice a week.

We have a small freezer and no equipment for canned vegetables. We just want to grow enough for fresh consumption of seasonal vegetables.

Growing enough Okra plants for 2 people to eat twice a week will pretty much fill up a 8'x4' patio and shade anything you may have growing under them.

I grew Okra and the plants are well over 6 feet tall but I loved the flowers they produced. My biggest problem was getting the pods picked at the right size, I'd look in the morning and too small, check again in the evening and too big. Pods which are to big became woody for the variety I grew but eventually ended up with shopping bags full of the right sized pods, I think I grew a dozen plants. One plant can give you 5 to 8 pounds and are heavy feeders so you'll need to fertilizer frequently in pots, with ALL the nutrients they need because many will leach in pots.

If I had that assortment of pots available. I'd probably stick the herbs in the one gallon pots. A couple seven gallon pots each for tomatoes, okra, and maybe three for peppers. Depends on how you treat your plants, but you will need to tend 7 gallon pots pretty heavily for those plants. You might be able to get away with twinning your peppers since they are bananas, they can solo down to a three gallon. Your tomatoes and okra for sure one per pot, and make sure that tomato is a dwarf or determinate variety. I wouldn't suggest trying an indeterminate variety in a seven gallon pot, those tend to need ten gallons plus for a successful plant. I haven't grown okra, so don't know it's container habits.

Succession plant your peas, leeks, chard, and choy in the rest of the seven gallon pots. 4-6 pots for peas, do a couple plantings so that as some pots are going flush, the other pots are starting to really go- by the time the first pots are running out of steam, the second set should be flushing in. 3 pots for leeks- use square foot method planting, transplant into the pots about two weeks apart. Technically one is supposed to be able to pack up to 18 in a pot that size, but I think you probably want to cut that back by half and do 9 per pot so they are easier to take care of. You can stagger out harvesting, and you may get a few more leeks than you are used to. But I figure doing a four staggered plantings between two pots might be a bit fussy for you right now. If you do cut and come again on your chard and choy, you can do 3-4 pots of those and keep them on a rotation of one being harvested, one or two recovering, and one about ready to harvest. Depending on the variety of choy you choose to grow, many of them are quick growing and you may prefer to succession plant that instead. And they can take up different space- I have winter choi in bins outside and a green bok choy in the garden outside and the winter choi takes up more space. On the other hand I'm groing Hedou Tiny indoors to harvesting in the little 1-1/2" cell trays that come 72 to a flat. They are tiny:) I'm harvesting radishes right now grown the same way too.

Not mentioned by the OP is flowers. I suggest adding some in. Pretty and helps attract pollenators. I'm fond of nasturiums for being wholly edible, pretty, and attactive to pollenators. Marigolds and zinnias are usually popular too. Some of your herbs can add to that too, like your basil going to bloom is lovely for the good critters of the garden.

Something that might be helpful to use are ollas. They really can help keep even interior soil moisture in containers. Don't feed in ollas, only use water in them. If you can work in composting, do so. While a large bin or tumbler is out for you, you might be able to set up a small worm composting bin. If you feel like you can be fussy, try looking up bokashi. There are also little composting machines now, but I don't know much about them.

Since you are hardly farming for subsistence, think more in terms of quality not quantity, getting high quality food when possible. Plan around when you will be harvesting each item. Learn from experience what does well. Worrying about excess food seems unrealistic, grow what you want to eat.