Don't worry, they'll fatten up big time in a few weeks.
Flush them, let us know where your PH stands. If your ph is off, youll have to flush her until you get her to a reasonable PH level.
I would pick up some Bloom nutes, Something like MASSIVE, Id get a finisher and some flushing agent.
Once your ph is right, feed them - first feeding:NUTES second feeding NUTES - third feeding Flush forth feeding NUTES-NUTES - FLush etc..
Run your Bloom booster for 2 weeks, finisher second last week and flush agent the last week.
This method has got me buds the size of grape fruits, no lie.
Hope this helps!