Obsessive Stuff

I need some help in working out if this is mania or if I could have OCD on top of bp. If it's normal mania behaviour, then I'll just assume it'll pass when my medication is increased and all the mania symptoms go.

I get obsessions.
They can be about anything.
Characters in a story, people, equations, books, anything.

Quite often I'll spend days or weeks just spending tons of time researching, or thinking about only that thing.
It becomes the most important thing ever to me.

So, for example, when I was about 14, I read A Brief History of Time by Stephen Hawkings, and then I spent a month or so working on a theory I'd come up with and having the deluded problems of thinking I was a genius and wondering how no one had thought of this theory before.
I obsessed about it totally!

With people it's rare, but can be odd. It's more normally a character in a story; I'll find that character's personal story compelling, and I'll then become a stupid 'fangirl' of that character for ages and write fanfiction and stuff.
It happens more with characters probably because I tend to prefer not to deal with real people to be honest - I'm still a bit of a loner, besides, I love Rob, and I don't even look at other men normally.
The only times I've ever had it with a real man is when they're really energetic and that energy clicks with me when I'm manic, and I'll get really excited about what they're talking about, and then I'll obsess about them for a while. Though obviously I try to push real people out of my mind as quickly as possible.

It's something I'm worried about now I'm at uni though; I'm worried I'll get hung up on some stupid theory or something and spend all my time researching that when I should be studying my real work!

Is this a mania thing?

Or am I more nuts than I thought?