Just skimmed more heavily in this thread. The thing about your situation is that you're not polyamorous. You're just looking for friends with benefits, and your girlfriend is okay with it. I don't have any beef with what you do, especially if your girlfriend is okay with it. It's just super lame to be calling yourself polyamorous when you're not. AMOROUS means love, you know. Sure, you're open to love happening if it happens to happen. But I definitely get the sense that you're looking for lots of sexual play that is fairly meaningless, and having a meaningful relationship may just be an incidental occurrence. I don't mean to condemn just you, but it's true that what you're doing is a huge cliche. That is, being a guy who wants to get sex from women and have those women not mean much to you. And then calling yourself "polyamorous." That's a crock. Sorry, but it is. If you were polyamorous, you'd not have casual sexual relationships; you'd have meaningful, deep love relationships, and your girlfriend would be okay with it. And if casual sexual relationships presented themselves as an opportunity to you, you wouldn't be interested. But you're very interested. You and your girlfriend are in an open relationship; you're not polyamorous.
That being said, there are a lot of couples like you who call themselves poly but who are really just in open relationships -- that is, open to have sex with other people without those sexual liaisons meaning very much.
I just don't like people dressing it up as polyamory when it's casual sex.