Let's be clear here, pumpkin, you're problem isn't because of men. Your problem is your internal indecision and general 19-year-old malaise. You're pretty normal.
Most people your age and even well into their mid-20s experience exactly what you're talking about. One minute they are rebellious happy-go-lucky sprites traipsing through life with vim and vigor, without any need for anybody else to make them happy. Kickin' tires and lightin' fires.
Then at some point, while you're sitting alone in your room staring at the ceiling fan go 'round, you realize that your life is empty because you have nobody to share your lack of accomplishments with. It's a common dance. I wouldn't worry about it too much. But I'll tell you this, enjoy your life right now while you can, man or no man. Don't wait for a man to make you happy because if you can't be happy single, you'll never be happy coupled up.
You'll have your entire late 20s and 30s to complain about these problems so wait until then and just enjoy your youthful body and spirit. You are not bi-polar. You're 19.
Honey you have a chronic disorder, it's called youth, I hear time usually clears it up.