Kinda difficult troubleshooting a previous grow. So unless you kept a detailed daily log it's kinda pointless.

But next time you have something that doesn't look right, give another holler.

After what you posted, I can see that likely your final pots are too small, (2.5 US gallons or so) possibly causing a late-flowering rootbound condition, and all peripheral problems that come with it. Doubtful it's as easy as that though. Likely a combination of that, not knowing your ph, other unknown variables...

I've never used CO2, other than a seltzer water experiment that ended in an ant problem and sticky walls. (and sticky pots, and sticky bulbs...)

NEWS FLASH: 2.5 oz per plant isn't crap. (depending on it's genetics, lol)