Not to dampen your hopes for a solution to your mysterious symptoms, but I've raised four kids to adulthood and I'm a nurse who happens to have bipolar disorder.....yet none of those attributes allows me (or anyone else in this forum) to diagnose you.

TBH, you don't sound bipolar to me---you sound like a pretty normal college-age guy who may be over-thinking things. That's not unusual, nor is it necessarily a bad thing; but it does indicate some generalized anxiety that probably isn't pathological, but a normal part of growing up and realizing that you're about to face a big world full of uncertainty. And that can be scary!

Trust me: online quizzes don't really mean you have the disorder. I can take one quiz that shows me to be severely manic, and turn around and try another type that says I'm mildly depressed.....and neither one accurately portrays my actual mood at that time.

Seriously, son, you don't want to be BP. The diagnosis does have something of a mystique to it, seeing as how so many celebrities seem to be getting diagnosed with it these days; but living with it is a whole different ballgame. "Night depressions" and moods that change on a dime are not typical of this disorder, although they do happen to the rare person with the condition. Which means you need to be assessed by a professional psychologist or psychiatrist in order to find out what, if anything, is really "wrong" with you. Sometimes it's not even THAT easy......bipolar isn't the simplest illness to diagnose, and then they have to figure out what flavor you have, which can be a lengthy process.

Best of luck to you in dealing with the uncertainty you're going through.