My first grow box - can anyone give me advice?

I've built a stealth box out of an old set of drawers. It's pretty small (16" deep x 36" long x 28" high) but Im really tight on space and need to keep the whole operation out of sight. I've got 2ft t5 high output bulbs (24w 6400k) made by agro Brite and can fit a canopy of 4 lights hanging above and up to 4 lights on each of the walls of the cabinet (total of up to 12 lights - I have 6 installed, will keep adding as the canopy is raised). It's a wood set of drawers that's got a sub floor built in with venting holes and a 3" high mini shelf built into the ceiling for the power cables and a hole cut for a carbon filter. I have a small 3" oscillating fan on a tiny shelf inside the unit for air movement and another one in the ceiling shelf to move air towards the filter. I've caulked around all seams to keep the heat in and lined the entire interior with mylar. The temp is keeping at 29c and I have 5 plants (auto flowering wappa from paradise seeds) growing happily now for 2 weeks in 6litre pots of soil with pH balanced watering and just started using dutch growth formula every other feeding. Been going with 18hrs of light a day so far, feeding when the soil gets dry.

Can anyone give me any guidance, tips or let me know what I might be doing right or wrong? I did my research but my supplies and space are what they are (no room for hps lights).

Really hoping I'm on the right track here - I probably have too many plants for the box but I can always find a solution for that if I'm over capacity when I get to that point.

Thanks everyone

pictures

No prob

You are gonna want to get some air moving in there, it will be able to breath with the back open, but you will still want a fan of some type in there to prevent mold and mildew

Any thoughts on the light setup? Am I going to get enough light/lumens for flowering time?