First grow, what am I doing wrong?

Hey MG! So this is my first grow, and I'll be honest I've been stressed out of my mind lately (no weed :(). Spent a lot more than I expected on my setup so I'd really hate to have my first grow go down the shitter. With that said;

-2x Fem'd Green Cracks (top two in group shots), 2x Fem'd Crown Royals (bottom two)

-3x3x6'5 tent

-6" inline fan with carbon filter

-Marshydro II 900, 24 inches from the babies

-Tap water out for 24 hours, ph'd at 6,3-6,5

-Fox Farm Trio

-Generic "Premium" brand soil, has perlite and I think tree bark in it (didn't know at the time that was bad)

-Temps: 20-28 celsius before transplant, 20-24 after transplant

-Humidity: 35-50%, but went down to 28% and up to 60% a few times

So I started the seeds in small 3-4 inches containers (smaller and about half the depth of solo cups) about 20 days ago. Everything was going great (almost too good to be true in fact), until the first set of true leaves started turning yellow from the tips, around day 13. Still using a sprayer to moisten the soil once or twice a day by that time.

I did some research and figured it could be either overwatering or nitrogen deficiency. For the following watering(day 15 or so), I added Big Bloom (NOT Tiger Bloom) and Grow Big at 1/4 strength. It's also at that time I started regular waterings (water until runoff). I noticed the next morning that it gave them a little boost, and couldn't see any signs of burns, so I figured they took it well.

Now over the next few following days, leaves started to droop, the yellowing got worst on the first set of leaves, and the tips of the second set started turning lime-green/yellow aswell. At that point, the one that was the biggest and nicest was now very droopy.

I noticed at that time roots were coming out the drain holes, so I let the soil dry almost completly (36 hours or so after previous watering). CR1 was still very droopy at that point. I thought maybe I should wait for the leaves to look healthy again, but I didn't want to risk them getting rootbound(24 hours ago).

I got 1.5 gal pots, proceeded to transplant them after moistening the soil a bit. Transplant went relatively well, the soil did crumble from being too dry, but didn't do much damage to the roots (I think), except for one small root that broke off on one. The roots were white, no signs of yellow/brown, but they were getting rootbound (you could clearly see the roots twirling around the pots walls). Like I said, these pots are like, half the depth of solo cups. Could that be the culprit for the yellowing and droopy leaves?

Since the soil in the bag was moist, I just gave a little water (with nutes at 1/4, as per a coworkers advice).

Today, the leaves are still droopy/wilty, but they are still growing. The fourth sets of leaves seem to be growing faster then it was before transplant. But on two of them, the second set of leaves seems to have started turning brown at the tip (where it was starting to turn yellow a few days prior). I'm thinking nute burn?

I'm pretty confused as to what has been going on. I am thinking it is probably a combination of being rootbound and overwatering, but hell if I know.

I'm sorry for the block of text, and I realise I'm suffering from overloving and overthinking. I'm trying to work on it, but no weed doesn't help with my anxiety.

Here are pictures (I have more, will upload if you guys want); http://imgur.com/a/gXayk

Oh and don't mind the weird looking one, I think it's mutated. Will add details if you want. I know they are still shocked from the transplant, so I'm gonna wait a few days see what happens, but I'd like to have at least an idea of what was going one prior to transplanting.

Thanks!

tldr; First set of leaves started turning yellow, got progressively worst. Leaves eventually started drooping. Tips of second sets started yellowing too, transplanted. Was rootbounded, possibly overwatered aswell. Am I correct?