You need to start feeding this little one... there are a whole host of organic nute lines out there but BioBizz springs to mind. Whatever you get, make sure it's got decent NPK and get some food into her! And definitely get some bloom nutes in her since she's going to be going into pre-flower any day now - at least within a week or so! Feeding should probably have started weakly (like 1/4 strength) in week 2 so do that the next grow. As far a pH is concerned, I would get it to 6.2 at the minimum since you have mixed soil in with the coco...
Good luck!