Depression And Bipolar Disorder I

I got to see my significant other today. Have any of you ever dealt with someone with depression? Maybe someone who's bipolar? Because my significant other may have depression and I think I'm bipolar. But I'm not sure about either. It's more of a self-diagnosis. He/she has no self-esteem and doesn't believe any compliment he/she gets. I have periods where I'm extremely child-like and happy, maybe overexcited. Then I get into periods where I'm extremely depressed. I think of death and suicide, I lose all emotion, and I just want to die then and there. I don't think I have a future. I think I have Bipolar Disorder I, meaning I experience Manic Periods (extreme highs, happy moods, iggly, fun) and Depressed Periods (extreme lows, suicidal, etc). Any opinions?
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