Curiosity compels me

I think I may be poly, but I'm not sure. I know I've felt in love with multiple people at once, for multiple nonconsecutive lengths of time, but none of that has ended well. (He is a jerkwad. She is straight, which rules me out of her dating pool. They (singular) would love to go to dinner with me if only we had something resembling physical proximity [I'm US, they're UK], which sure as hell felt like a turn-down, and neither of us has said a word on the subject since. Etc.) But I've never been in a relationship that lasted more than three months offline or nine months online, never mind two relationships at once. So I don't know, really.

How does one figure out whether one is actually poly?

(fyi I'm a singular they.)