Chloe - Are you sure it is legal to have your belly button pierced at your age?  I thought you had to be at least 16 in the UK and as you mention the cost being £50 assume that is where you come from.  As I understand it infections are quite common in belly button piercings, so you do need to be extra careful because of your CAH and ensure you go to a reputable place.  I do understand you wanting to show of your flat, smooth stomach after all you have been through but why not do this with crop tops for now?