Lemon Haze Auto

it's been pretty rough, although this was to be expected on my first grow. the largest plant and the yellowing runt are on day 21 from sprout. I started them in smaller cups and did the unadvised transplant of an auto. the smaller runts root ball came apart and I almost dropped it, I kind of saved it however the roots landed kind of sideways, which I believe was one of the reasons that caused this issue. the second 2 plants, the small one with yellowing cotelydon leaves and the much larger healthy green seedling sprouted at the same time 10 days ago, obviously one is exceptionally healthy and the other is yellowing. Overall, I have a few questions and concerns from my fellow cannabis green thumbs out there! I know I've over watered all of them except the largest one at some point. now I'm kind of an underwaterer lol. I have not used any ph meter or water and I've only used big bloom by ff. In about 3 days I'll have ph solution, digital tester, and fox farm grow big for npk nutes. that being said. please give me some advice, Insight, and closure because I'm worried I won't have anything but 5 grams dry weight! I even feel like the nice healthy large one is going slow and is short for 21 days. what do you folks think? thank you!