I think you're doing great. I don't have much to add. I like what you are doing. I don't know how feedable it is abut a giantess route would be sick. So far it seems like every route includes a little bit of the others including getting taller. One that focuses on the girls growing primarily bigger and getting strong/more curvy as well would be a nice addition.
Some feedback I have is that as it stands there really isn't much dialog with the girls aside from the meet. Adding in some lines for them for quests or challenging Luna would make it feel more like a team then generic battling. I'm sure a lot of people would also appreciate a shot description of their growth when the level up an transform. The NPCs almost seem like they got a little more love with that then your team. Just some feed back to help the player feel a little more connected to the characters.
Not sure if it's a bug but I don't seem to be getting 2X XP from the clown fish or lucky fish like the description implies. I only seem to get the banked bonus XP. I've tried feeding them a bunch at once, feeding the singles, and feeding them id battle. For reference I've only been doing this with the wolves and not the weaker enemies. If it is supposed to grant double XP, a double XP counter in the info box would be nice. If it's not actually double XP I'd reword the description to bonus XP.