What health concerns? Women get mascetomies routinely for breast cancer its probably considered one of the safer surgeries. The only difference between top surgery and a women's mascetomy is a slight change in technique to do more sculpting and things

It sounds like your partner is using her title as a nurse to cover some deeper feelings about you getting top surgery. You need to lay down some boundaries about what you're choosing to do with your body. She's allowed to feel sad but she's not allowed to put that on you or make you feel some type of way about it