Plants look healthy, your temperatures are okay. I like to keep my temp as close to 80 without variation as possible with LEDs, I think that works good. Looking at your setup I would suggest if these plants are more than about three weeks old that you have been under watering. It would be a lot easier to tell if you had a grow log on the site and I could look back and see what you've been doing. But, once the plants are about three weeks old you can water to run off and you should. If you don't slowly soak the pot and get run off after about your first 10-14 days you risk your roots drying out and dieing back each time you water. That will keep your plant small.
Lower temperatures like the 72 will keep your plants smaller. If your humidity is too low say 35% or lower that will keep you small. If your medium is too hot meaning too much nitrogen that will keep you smaller.
Like I say your plants look healthy enough I don't believe you've had too much nitrogen, so I would consider temperatures and watering habits.
Where I'm currently growing
Where I'll be Nov 1st