Fastbuds grow

Well they are all in flower. They are far from what I was wanting in terms of size of plant. They are looking very healthy though, so I suppose I will just try and grow some nice dense bud with what we’ve got! They are excellent plants, the fault lies with me and not really having a firm grasp on how often to feed/water and how much nutes to give and when. I feel I either give too much or too little, not often enough. Any tips on how to grow a bigger plant are greatly appreciated!