My Struggle w/ Anxiety

I have had anxiety for as long as I can remember, though that doesn't say much. I'm 15 years old, and don't remember half of my life. I've had some traumatic events happen to me, and I guess I just wasn't strong enough to properly deal with them. From my understanding, it all started when I was a young child, a toddler. My father had anger issues and occasionally hurt me and my siblings. It wasn't bad enough to get him sent away, so there was really nothing we could do about it. Being a little kid, I actually thought that I deserved it.
My anxiety didn't really come out until first grade, when my mom got sick and almost died in front of me. I thought she was dead, and that made a huge impact on me. After that, I had horrible separation anxiety, so school was, obviously, horrible. My 1st grade teacher did nothing to help, in fact, she just made it worse. She was horrible. I think that's where the anxiety about school started.
In 2nd grade, I switched schools to a private school because I was way above my grade level, and we just hated the school system. I went to the private school for 2 years, 2nd-3rd grade, and it was mostly fine.
Then, in 4th grade, I went to another elementary school in the district, and it was okay, not as good as at the private school but I made it through.
When I switched back to the first school in 5th grade, everything went to crap. I don't know what started it, probably the memory of 1st grade. I didn't want to be in class. I wanted to go home. I used to hide in the bathroom stall and skip class, usually crying.
6th grade was different, because I went to a middle school that year. It started off okay, but then it got worse, and stayed that way through 7th grade. I sometimes ran out of the classroom and hid in the bathroom. I couldn't go to gym. I thought everyone was out to get me.
In 8th grade, I finally did it. I walked out of the school. I tried to walk home, and got way lost. This resulted in a suspension, which was exactly what I wanted. I mean, no school for 2 weeks? So then it became a reasonable option in my mind. I still haven't been able to shake this. I've been suspended upwards of 7 times for that.
9th grade was shit. It started off okay, but then about 1/6 the way through the year, I was put on half days, which I started  being unable to attend even that. Most days I stayed home for fear of feeling anxious. Eventually, I got online courses, which I didn't do because they reminded me of being in school. I almost failed.
Almost.
I hope that 10th grade will be better.