Ok first of all you are a long way from needing bigger pots in my opinion. The pots you have can be used for quite some time. Tuff to tell from the pics, but a bigger pot is the least of your issues.

Smokinlowrider is correct with the 18/6...in my opinion. 24/0 is what some people prefer but I know my plants flourish under 18/6 and stress under 24/0.

Your space is enclosed, yet you leave it open?

Which one is it? Open or closed?

Make up the schedule and live by it. When you leave the unit open, you are allowing light to escape...

I said before, you will need to remove the heat....no ifs about it. a fan blowing and an open door doesnt remove the heat.

Get rid of the heat or the heat will get rid of the plants.

Good luck.