thank you so much for your thoughtful responses. I'm digesting all the things that everyone put forth (including the piece by Poe). I think one of the the most important things that I'm trying to take away from this is that it is pretty normal to feel this way when beginning this way of life and that I need to struggle through it if I want to grow. If I wasn't so into this girl, I think things would be a bit easier.
To clarify some of the questions people asked, we do hook up with other people some times, I just don't like the way it makes me feel knowing that she's doing so. I'm sure she feels similar about me.
That my shitty feelings come from deep fears is just what I have deduced, as all feelings of jealousy originate from fear. I would say that in reality most of our fears are irrational but some are rational.
My reasoning for wanting our relationship to be poly probably is more of a reaction against monogamy rather than a desire for polyamory, but these things aren't necessarily mutually exclusive. I do not like the control/restrictiveness of monogamous relationships. I see polyamory as an alternative to this. Potentially, a way to be with the person I am in love with long term without having our other needs/desires stifled.
Thanks again to everyone
I'll try to provide some type of update...