What kind of symptoms are you having? There are several types of bipolar disorder, with differing symptoms.
If you really think you're showing that many symptoms, you definitely need to find some help, these things tend to get worse when left untreated, and you don't want that. If your friends and the internet are right, you need to know, and soon; if they're wrong, you need to know what really IS going on.
As far as your mom goes, if you don't want her thinking you're "totally insane," then she needs to know what's really going on. She should know anyway, even if you don't want her acceptance.