I once turned my ankle leaving the school grounds, slipped, did a somersault in mid air which pulled my back and my shoulder and landed on my hip. I was in agony, but all my friends just laughed. It probably had been very funny from their point of view (this was before camera phones, so I guess I'm lucky no one was able to film it!) but I wasn't amused, especially since, instead of calling for a lift home, I put a brave face on it and hobbled all the way trying not to cry.
I wish I'd been diagnosed earlier on at school. As it was, I usually did PE when I could, but got to sit out and work on a written sports project (usually about horses) when my knees were badly swollen. We once did a whole term of trampolining, which was probably not good for my knees and ankles but because it just "twinged" when I made impact with the bed of the trampoline, I wasn't allowed to not do it. However, I did get out of sports day a couple of times (I was always on the tug of war team and went home with subluxed shoulders

) and usually got out of netball and hockey because I found running so painful. One year I was told I HAD to take part in the sprinting and cross country runs, or I'd get detention, so I just walked the course with my asthmatic friend

.
I agree you should get information from both HMSA and the EDS support group - as these are information leaflets from registered organisations/charities, no one can say you're making it up. I wish I'd known about the HMSA when I was still at school - it would have made things so much easier, and I could have gotten a lift pass if I'd been able to explain that it was a permanent condition that's always there even on good days, not one that just comes and goes. I often had to walk up two flights of stairs to lessons, even when I was on crutches!