I scratch and hit myself and idk why

i don't really know what to say since everything is in the title but basically, I already did this as a child. when I was upset I would hit my head to punish myself or idk. I stopped, but I started doing it again since like last year ig? When I get even just a little bit upset, I hit my head, I slap my face, my thighs, I hit my phone against my head, I scratch my face and bust. last time I had huge marks on my chest, now I have a wound on my cheek. here are some examples of what made me do it: - overthinking - arguing with a STRANGER - arguing with my ex friends -bc I lost a game in CODM (I stopped playing) - people telling me I'm glorifying mental illness(?) or some other dumb stuff like this.

It's killing me. I hate it. It just feels like the right thing to do when I'm mad. I've tried hitting a pillow, or screaming into a pillow. nothing works. my friend told me I MIGHT have BPD (might in all caps, bc some ppl said I was glorifying mental illness💀) but we're not sure, I just think I have anger issues and that I need to learn how to control it. I used to have a therapist but we stopped seeing each other. I know it's bad, but I don't feel comfortable with talking with a therapist, and I just feel unable to do what she used to advise me (for another issue, I never told her about me hitting myself)

I would also like to know if this is considered SH?

please someone help me bc i can't take this anymore.