I know exactly what you are going through migraine_girl. I started getting weekly migraines when I was 14, my first year in high school. My teachers weren't understanding at all, they said "we can help you get your work in on time" and stuff like that, but they actually made school harder for me. By my junior year, my migraines were daily and I wasn't even attending school once a week. I was pretty much homeschool, with myself being the teacher. In my senior year my school decided that they weren't going to deal with me anymore and I had to drop out. I did get my high school diploma by attending night classes at an Adult Education Center.
My doctors started telling me that my depression was either causing my migraines or causing me to make them up. That made me feel so much worse, I was like "I'm depressed because I have no control over my life anymore!" I don't get invited to social activities for the same reason as you.
I'm now 18, living with my parents, and attending college online. Online college is great for migraine sufferers, you don't have to worry about your attendence record. Plus, your professors never see you, you don't have to worry about them saying "But you looked fine yesterday!" With online classes you can work more around your schedule.
There are a lot of people with migraines that have similar experiences. If you ever need to talk or vent to someone you're more than welcome to email, YIM, AIM or MSN me.
I wish you the best of luck,