DC, as gently as possible, I would like to say I am worried about you. Perhaps, while you're single, it would be a good time to explore some options on how to help you manager your choices to help keep yourself, and your partners, safe both physically and emotionally? For example, drinking excessively can cause so many problems, including the possibility of sexual encounters you may not have consented to or be aware of--rape--which would leave you in a very bad situation physically and emotionally. Or, as you say has already happened, having unprotected sex, with all the possible consequences.
Generally, poly is more than just sleeping with different people with whom you are not in a relationship. That is more often just called "dating" these days, or (in other contexts) swinging. Becoming involved, emotionally or physically, outside of a relationship, when the partner in that relationship is unaware and consenting, is called cheating, not poly. This is true when you are with someone who's partner isn't aware of your encounter/relationship, just as much as it would be with your own partner. Poly is about communication, and definitely about consent and respect, which are all necessary to be safe and happy (frankly, all relationships should be about those, not just poly). The partners who you've said made out with you after saying they have a girlfriend (which a general person generally says more like "My girlfriend and I are in a poly relationship, are you okay with that?", whereas just leaving it at "I have a girlfriend" definitely implies she doesn't know, and they aren't poly) aren't respecting you, or their girlfriends. Which means you are very unlikely to be the first person they've broken that trust with, and tells you a good bit about the level of safety you might expect from them, especially if you are incapacitated.
I am not a prude, and no stranger to partying (I was a traveling Bud girl at one point), but safety is a real and serious concern.
As Kevin suggested, more reading, and possibly some help in learning good decision making, would be a real benefit as you move forward and explore poly.