It looks like the symptom of over-fertilizing. What are the white particles on the soil surface the the plants if you don't mind me asking?

oh that white stuff is some leftover perlite I threw in
Someone told me I am over watering, can that be the problem?
I don't think I have used too much fertilizer, potting mix is coco peat, compost and perlite

I don't know where you're located but if you're anywhere in the North America, growth is going to be slow. Overwatering or fertilizing may be an issue though. For overwatering, that's easily fixed --- wait until you see the plant wilt before watering.

What are you using for ferts?

Is that particle board/plywood? The glues and chemicals used in processing can't be good for any soil.

Kevin