Well first things first put your lights on 18/6 and get at least 6 hours sleep :P

OK so its in a closet right - not another cabinet inside the closet?

If you are using the whole closet, do you store other stuff in there? Or is it 100% a "grow area". Light leaks you have to fix - they may compromise the darkness you need to flower and let light in as well. That heavy duty black polyvinyl weatherstripping should work to block the light from the door, but you need to vent.

Lemme know the closet situation, if it is a 100% grow area, and what the dimensions are. If not, then you will have to build/install a cabinet inside the closet - what dimensions do you have to grow in?