I speak some decent Japanese. I almost guarantee it's not "Her breasts are exposed", as the subject is almost always implied. It probably says "breasts showing", and it's implied that of course we know who's speaking.
Translators often add pronouns where there is none, because well, most of the time they need to. The problem is it often takes a guess.
Putting "My [breasts] are [exposed]" is perfectly okay because you're not adding information. You're simply putting it in an English context from a Japanese one.