Shirt shopping Very Aggravating

Hello everyone, I am 4 weeks post-surgery double mastectomy. I am a T-Shirt very casual dress kind of gal. I wore a size 3X shirt before and now everything is too big. Some of my other shirts show the top of the sports bra or a bra let when I try them on. I did wear a size 42D or DD bra before. I have found that some of the sports bra or bralettes tend to roll up from the bottom. I do have a bra fitting later in the month and will go to get advice. Does anyone have any suggestions on what brand of shirts or what type would work better? I am still the same size everywhere else.