Doing something wrong

So I didn't start feeding them until they were 6 weeks old now I just gave them their second vega matrix feeding. I just transplanted them from 5 gallon pots to 10. Is that whey they haven't grown much for a while? I also think I underwater them because they seem sometimes droop and feel dry after just 2 days. Anyone know how many gallons of water is good for 10 gallon pots cause I watered them until water started dripping from under and then added the feeding mixture in 1 gallon of water and watered again but I think a lot of the feed drained from the bottom. Also I didn't have enough soil so I potted them shallow will it be fine like this?

The rule is when it's time to water, water until you see proper run off.

If you're not sure about the dryness of the pot soil get a $5Can hygrometer and stick it in one of the plant pots. I wouldn't go by what this meter said like but I would use my own judgment and check it with this meter. Two opinions are often better than just one

TBO as long as you get the feedings and watering correct it's all a go Don't worry about that bit of feed going out the bottom. it's all figured for that in the potted instructions on the fertilizer package. It wouldn't hurt to thin/dilute the feed with a bit more water as stated by the instructions on feeding days, as long as in the end they get the same amount of nutrient.