im so sorry your having a hard time with your baby, i have 2 dragons and thught they were somewhat hardy but all i have found is they love to stress you out for no apparent reason, lol, thats what makes them unique.
ok so shes eating around 14-20 a day, at 16 weeks she should be fed ideally 3 times a day, obviously i understand thats not always the case as of other commitments, work, etc. each feeding you should let her eat as much as she wants in a 15 minute sitting, they could eat up to 100 crix a day!
her pooping in the
bath isnt a bad thing really, more hygienic and easier to clean and yes it does somewhat go all weird, lol.
with the lighting and heating, you have to have a white basking light in conjunction with your uv as it may do her some damage, i personally use a reptisun 10.0, 60watt white basking light and a ceramic heat emitter.
the calcium she should be getting
once a day for 5-6 days a week, the multi-vits
once a day for 2-4 days a week.
i too am from the uk so understand your frustration, in the us they call some salads different to what we call them, lol,for live food i would feed her crix, locusts, butter worms on occasion as can be a tad fatty, wax worms maybe one or two a week as they are extremely fatty.
for greens i rotate mine so they have a couple of different greens every week, it doesnt matter how much greens shes eating as anything is great for her age, offer them daily whether she touches them or not, i use spring greens, fresh greens, pak choi, cress, watercress, pea shoots and rocket, mine love their rocket, you can get all of those things from tescos, sainsburys or asda, or probably any major food store will stock those.
as for her belly i think as long as shes got a healthy appetite, her weights remaining stable or climbing, her pooping and shedding are all fine and shes not showing constant stress marks or a
black beard then i wouldnt worry, she may be stressed even if you dont think she is and shes not showing typical signs, like i said they love and know how to freak us out! she may simply be puffing herself out. also a happy healthy dragon should have a round porky belly, its what they are known for, lol.
is there any chance you could post a pic so we could get a proper look at what exactly you mean about her belly?
i hope i have helped you out some more.