You might be watering too often, or not often enough.
- Symptoms are the same, so you gotta use your memory as to when you watered last. Tho it could be other things, but it's usually one of the two.
If you're truly considering starting over, when they've just started to preflower, then take a look at my Quick One diary and compare it to yours.. I fucked up really bad a few times lol. You'll see how good yours actually look. ^_^