I think what happened here, and what shorted it's growth. was he almost immediately took it from 24hr light, to 12/12. Putting it into 12/12 makes the weed think "hey i need to start working on flowers!!" Thus not giving the plant itself enough time to spread out and develop itself to hold the weight of the buds it may produce. .
For future grows bro, start seedli8ngs off at either 24hr, or 18/6. I've got about 12 sprouts from some mid-grade crap from around here, and they've been on 18/6 for the past 5 days that they've popped up. I'll keep them on 18/6 so i can either scrog, LST or top them for the next 2-3 1/2 weeks. Then i'll switch them to 12/12 and see how many females and males i end up with. (Ofc i'm yanking out the males soon as i confirm sex.) What i have now would be my first "full-scale" grow setup.. have had previous unsuccessful attempts at outdoor growing.. so going indoor now.
Good luck man, hope this helped! SUB'D