I need help & I keep hurting myself?

I feel like I hate my life. I go into school, and I'm scared to go around because one boy sometimes grabs me and asks for a fight as a joke, and another just gives me **** whenever possible, both of these boys are friends but they never do it together. Then there are these group of lads in the year below, last year I was assaulted when the gang of them approached me and one head butted me. In the group of them there was 15, there was 1 of me. I feel scared to walk around school, I have spoken to the school nurse, I've had counselling I've spoken to my mum and nothing will stop me worrying. I want to move schools but my mum won't let me, she thinks it will add even more pressure because my grandad died 2 weeks ago. I don't know what to say or do to convince her moving will help because I know inside it will, I have tried everything and school keep saying to her how they will sort it and she listens to them not me. I've been self inflicting harm too and I just don't know what to do, someone PLEASE help...