Does this sound like Bipolar disorder?

I've done extensive reading on the internet about Bipolar disorder. I often find myself in a normal mood and suddenly something would trigger (sometimes nothing in particular) a severe depressive state wherein I find myself suicidal. I feel like I could just go to the nearest bridge or building and jump. And afterward, when my mood is better, I can't believe that I wanted to kill myself and even the thought of it scares me. I understand that Bipolar disorder is very difficult to diagnose and this short paragraph doesn't say much about me but I don't think that this is normal and I'm really worried that one day the sudden bouts of depression would get so bad that I'm actually going to kill myself. Where should I go from here? Can a normal GP help in this case? I'm weary of mentioning the suicidal thoughts because that would mean that by law my doctor has to put me in hospital. How do I get around it?