Your pic:

{{gwi:85321}}

Hello,

Mint does better outdoors, but can be grown inside, too. It need a lot of light and fresh, circulating air.
If the window is low light, and the air dry/stuffy, mint and other herbs grow spindly and/or acquire insects.

You said you see mint all over the city..Do you mean outdoors?
Plants looke their best when grown outdoors, especially herbs like mint and basil.

The plant next to the mint looks like Aglaonema/Chinese Evergreen. Not a positive ID.

Aglaonemas should not be in the same window as mint. Mint needs bright/direct sun, Aglaonemas do best in bright, in-direct sun.
Which direction does your window face?
It's either too sunny for Aglaonema, 'which would fade leaves,' or too shady for mint.

Aglaonema soil needs to dry a little between waterings, especially during winter or rainy days. The top of soil should feel a little dry..Soil should never be muddy.

Ficus, Rubber Tree. The reason your leaves are growing small is your plant isn't getting enough sun. Ficus need a lot of light.

Syngonium. I can't see any yellow...perhaps it's variegated? If leaves turn totally yellow, it could be over or under-watered.
Syngoniums shouldn't sit in shade. Many say they're low-light plants, but it's untrue. They need some light.

Fertilizing doesn't necessarily mean a plant will grow or be in perfect health. Fertilizing and light go together.

Hope this helps.

Purple, thanks for posting the picture. Toni