Hey Growmie,
Judging from the looks of your soil and the size of your plant I would say she's suffering from overwatering which has seemed to stunt her growth also, she should almost be ready to flower by now. You also may want to consider giving her more light 50 watts isn't going to be enough to give her optimal growth at this stage. Hopefully, I answered your question and remember ..."Happy Growing" and "Free your mind one puff at a time".