Air Flow Question??????

I wasted a whole month of flowering time by not ventilating. PLEASE OH PLEASE, anyone who reads this PLEASE make sure you vent! I thought they would flower because they were still growing and stretching but NO they didn't. All I got was preflowers and thats it. STUPID STUPID STUPID!!! I know venting is important and I don't understand why I didn't vent but its time to deal with it. So this is what I came up with. I am going to add two six inch wye's into the vent. One wye at the "in" side of the fan and one on the "out" side. This way I figure air will flow through the room at all times. More with the fan on but still air will flow. I have one damper and waiting on money to get a second so that I can install to control airflow in and out.

Anyway, does anyone think that I can make my vent system better or different or what? All comments welcome.

Right now the vent from "in" and the light is disconnected to allow airflow, to stop wasting time. I drew a ghetto ass pic but the file size is too big to upload so I don't have a pic at this time.

In my room, I'm running 1000w and I use a glass sealed light which is vented through a inline fan at 500cfm, then that fan exhausts through a tube that vents to the out side.

I have passive intakes "holes cut in back of grow cab" which draw in plenty of air due to the lower air pressure in the cab. "cuz the air is being vented out"

hope this helps