This does sound a lot like borderline behavior - I'd suggest getting the "dummies" books for both borderline and bipolar and doing some comparison on symptoms. They have some overlapping symptoms but a lot of the borderline behavior and thinking is pretty distinctive, so see how well you can relate to the examples and stories about people with these different disorders. I found that I could not really relate to borderline (BPD), even though I've had some BPD-like symptoms, but the bipolar (BP) behaviors and symptoms were spot-on, and it was a little freaky because a lot of the bipolar behaviors were things that I've done all my life and didn't realize they were symptomatic.

You might be able to find the books at your local library, but if not, they are super-cheap on Amazon, only about $10-$12 each. Well worth the investment if it helps you get some insight into what's going on in your life.