size pots

if you have a small pot growing a medium sized plant does that mean it will grow smaller

You can grow a plant in a dixie cup, I don't suggest it but if you look around here in different forums you will see it. Your yield is reflective or root ball, size of plant, lights, nutes and several other factors. Basically if you keep a plant's roots too confined they will not be very healthy or have the ability to process water and nutes correctly. Yes experienced growers can manage in less than ideal situations but I don't recommend it.
I would suggest to use the biggest containers you can, try running plants side by side in different size containers. This is only way you are going to know for yourself what works or doesn't work.
Happy Growing and good luck