Dear OCA (sorry, previously addressed wrong person),
I am also a college student with bipolar II disorder. I went my entire life unmedicated but with all the signs. Finally, while in grad school, I started to feel as if I was having a nervous breakdown. I went to the doctor and she diagnosed me. This was two months ago. I also suffered from severe insomnia. I had to work about 30 hours a week in a highly demanding job, and on the other days would drive 160-mile round trip to school three days a week. All this while trying to maintain a 4.0 GPA. It was a nightmare from hell! When I got diagnosed, I was totally relieved, but faced the same dilemma as you - whether to tell or not to tell the school. I decided to tell, and it was the best decision I ever made. They immediately stepped in and helped me end my job (which was a requirement for my degree), and my advisor even offered to talk to my teachers for me (without revealing my illness), asking them to excuse my absences for medical reasons. They didn't even require me to give them doctors' notes or anything. Very, very supportive. Turns out, they face this sort of thing all the time, and they were even telling me that they have had to deal with much, much worse circumstances than mine.
I encourage you to at least go to your school counselor. The information you give them is confidential. But they can step in and help you. If you are close to someone in your particular college if you are at a university, go to them and tell them that you are having some medical issues and need an advocate.
They can't help you if they don't know what's going on.
However, it is your choice and your choice only. But sometimes there are medical doctors on staff at the school who can prescribe medication. Is there a counselling center or health services? If so, go there.