Salaam - Struggling with PE and Family Expectations

Assalamu alaikum, I have a very religious family and I live in Europe. I’m only allowed to wear abayas to school. Last year, in the first term, I had PE every week but couldn’t take part because of my clothing. When the teacher asked me to join anyway I felt uncomfortable, and around that time I started getting picked on. So I decided to sit on my phone during every lesson. Eventually my contact teacher changed my schedule and I didn’t do PE for the rest of the year. I’ve since moved to a different school, and I think it’s on record that I refuse to participate in PE or physical activities. My new school is a lot stricter. I’ve asked my mum about wearing trousers for PE, but she completely dismissed the idea. Lately I’ve just been skipping every week, but it’s my last year of secondary and I’ve received a letter saying I’ve missed too many PE lessons and I might not graduate. Whenever we have parent–teacher meetings my mum agrees with the teachers in front of them, but in private she’s critical and shames me. I’m really unsure what to do. I hope to get into the high school I want and I already struggle academically. I don’t know how to handle the PE issue without going against my parents or risking my graduation. JazakAllah khair for listening.