Stripped shirts are supposed to be good at covering breast growth, to a point, but I don't remember if you want vertical or horizontal stripes. Breast pockets also help.
I began to realize as I got to a certain point in loosing weight that I am not just fat, but that somehow I had developed breasts of my own. I have no idea how it happened though I'm guessing maybe the water from living in a farm/rural area, or maybe a certain habit, but I'm not complaining. And there was one nurse practitioner I went to, for me knees, who started asking me about my testosterone levels after she had me lift my shirt up, and mentioned I needed blood work and maybe shots of testosterone. Never before do I think I have ever seen such a total and utter lump of incompetence. And I finally got to yell at someone for all the stupidity of the medical field, and that felt great to finally get all that out.