3 weeks into flower and my buds are tiny

[indicadom]

I have 4 white widow x big bud, a white widow x skunk and a cotton candy 3 weeks into 12/12 and the buds are real small. I saw a white widow online, same age with like 5" tall buds. I grow hempy, feed every other day with gh nutes, ph the water to 5.6-5.8. One 400w hps hanging 12"above them.

Impossible to determine, could very well be your skill level, light level, or genetics of the plants.