I'm in college and what has helped me tremendously is talking to my school/professors about accommodations. Your school should have a student assesibility department or disability service where you can apply for accomdations
Some of mine are lenience on absence policy, basically all my absence due to fibro sick days are excused, note sharing because it's hard to focus when in pain, and extra time on exams so I can get and walk around or rest my neck if it's too long
I hope this helps!

I'm currently in college and planning on graduating this December. I'm an elementary ed major so I want to be a teacher. There are a lot of days where I struggle to get through the day. Somehow I end up doing it. Last fall I did have to take medical leave half way through the semester as I was in a really bad flare. I used to be involved in multiple organizations with leadership positions on top of my classes. Now I'm still in the organizations but no positions and taking 12 credit hours. I found it helped to space my classes out to ensure breaks and free days. I also worked with my school to get accommodations. Those things really helped.

I know two people that just recently graduates from college that had bad fibro. One guy and one woman. Both scheduled classes later in the day. Both signed up for karate and started to smoke pot to help them. They said it helped them both immensely.

I went through the same problems - you are not alone. When I started to miss more school than I was attending, I re-evaluated. What was it I wanted from life? Is college the only way to get there? For me, it wasn't, so I ended up dropping out, and now I own my own business.
But if college is the best path towards the future you want, don't give in. Listen to your body, and maybe cut your course load down, or take online classes. Talk to your school about a disability plan, or at least tell your teachers about your fibro. Letting them know isn't asking for special treatment, but it does help them to be a bit more understanding. I hoped this helps, and I'm here to talk if you need it.