The good thing about troubleshooting plants is that there is a finite list of things that could be causing your problems.

Lights - I don't see any burnt tips, and your plant canopy isnt thick enough to block light yet.

Temperature - 16 degree swings is a bit much. I assume you're on an 18/6 schedule since you mentioned temps with the light off. There isn't any difference in growth between an 18/6 schedule and a 24/0 schedule (it's been argued to death!), so I would keep your light on 24/0 to keep the temps in the 74-78 range. The plants will be much happier there. If you're flowering already, well it seems a bit early to me, and I'd wait until the plants are healthier.

Watering - it's possible you're overwatering still. You didn't list your watering schedule, so it's hard to critique it. My watering started out at every other day when the seeds first popped. Now it's every 3rd day. Once I move into a pot your size, it might even be a bit longer as more soil holds more moisture. Make sure the top inch of the soil is DRY before you water. If you need to, weigh the plants before watering, and about 30 minutes after watering. They should add a lot of weight!

Nutrients - Fox Farm Ocean Forest is good soil. I've seen people go with zero nutes for the first month in FFOF, and their plants looked wonderful. I'm not totally clear whether you're in OF or HF right now.

pH - could definitely be a problem. I hope you got some pH up and pH down as well as storage solution to go with your meter. Cant diagnose this one until you get your meter.

You've got a few good sized plants there. If I were you I would make a test plan and see which plants respond the best.

Plant 1. Wait another day and a half to water each time.

Plant 2. Keep the current watering schedule, but raise the nutrients.

Plant 3. Keep the current watering schedule, add 25% nutes.

Plant 4. Keep your current schedule of watering and nutes.

If I had to make a guess at this point, I would say that you're watering too much, too few nutes, or the pH of your water is locking out the nutes. One of those three.