Mental health

I have never been diagnosed with anything I actually have a dr appointment coming up though to do that. But I’m like 90 percent sure I have ADHD and everyone around me thinks I have it to but what are some ways to manage it as a women. I heard it’s different for women and males and my boyfriend had ADHD and has been diagnosed but I feel like we are different about it. Also this next part is hard for me to talk about because I have never told anyone the only people that know about this is my mom my boyfriend and my sister but when I get angry or frustrated or upset I punch or slap myself in the face and head. I have been doing it for years now, every time I feel like I have got it under control something happens again. Im afraid to talk to the dr about it, the chance they might send me off to the mental hospital or something. Any advice or tips??