Thank you Anton. Do you know why their leaves are shrinking like that ? Do i not give the plant enough water ? I tried to water it but it didn't improve much i'm scared i might overwater it. I don't know what's wrong.

You could try adding some grit to your mix - IMO, 2/3 soil is too much. I would recommend using max 1/3rd of soil. That way you'll improve drainage and worry less about overwatering.

Portulacaria likes just a bit more water, just don't over do it. Sunlight is good for succulents, maybe they are not getting enough light indoors?

Are both in containers with holes in the bottom? They must have holes

I would let the first one just recover from possible overwatering. Stick a skewer or pencil or chopstick in the soil of the second one for several minutes. When you remove it, you can see if the soil is damp or dry. You can use this technique any time to decide about watering. Good luck.

I would gradually transition both to more direct light.

Thank you Rina, i can add more pumice into the mix. Is it enough ? Or should i buy charcoal, etc ?

Thank you Socks, I didn't think of the pencil trick ! The containers don't have holes in them... But I only water them little by little. Is adding a layer of stones at the bottom enough to substitute the holes ?

I'll try to give them plenty of sunlight.

Unfortunately, stones won't replace the purpose of the holes at the bottom of the pots.

You absolutely need pots with holes. Stones, watering little by little might work for a while but your plants will not do well at all in the long run. Terra cotta is best but plastic can work too. They are inexpensive. Don't buy too big.

Plastic pots are just fine if you are looking for inexpensive - you could get them for free from anywhere where they recycle (our garden centers do, and stores like Loblaws - food store that also sells plants in season - too).

And YES - pot/container for any plants should have drainage holes. Use saucers underneath if concerned about water overflow - they should be emptied about 15-20 min after watering.

No point of buying charcoal, get grit if buying anything. I buy 50lb bags for just about $10 (C). If you have pumice, use that instead of perlite as I already mentioned. No stones/rocks at the bottom, no sand (I know you didn't say sand). And if using any soil in the mix, make it smallest amount of all amendments.

(I don't use any soil, just a grit, perlite and turface).

Also when amending soil it's very important to completely clear any old soil off the roots before replanting and waiting at least three days before trying to water.