I always shower with my bag on. I use a one piece. I have no problems with adhesion, I just find the sides get mushy and then when they dry get a bit hard so they dig in, so now I cover the edges with brava elastic tape although any tape that keeps the edges dry will do the trick. This stops the mushy sticky sides for me. Jano puts a shower cap over hers but when I tried this it still got wet, I didn't stick it on though since you might as well just tape around the side of the baseplate. Micropore tape like they use in hospitals is great and isn't too bad for the skin. Cheaper than brave tape if you have to but it.
Good luck going back to work Ita, I'm sure all will be fine. Just make sure to take everything you need to change, clean up and change clothes just to be on the safe side.