"They're being very patient and understanding with me about the insecurities I've expressed since this is their first real follow-through of anything with a third."
I assume they also have insecurities (obviously) you're being patient and understand to them too right? The difference is you feel more vulnerable because you have to go to people in the established relationships to talk about your feelings, they have each other to talk to, and are probably talking to each other but not you as much as they should. Just don't want you to think you're being the insecure needy one, I have seen a lot of 3rds feel that they are needy, or be called needy because they are the ones who have to start any conversation that hits the hard topics since they aren't always included in all the ones the couples are having in private so don't have a clue where the other two parties stand.
For a triad to work (OK, I haven't ever been in one, but I read a lot!) all three of you are going to have to communicate with each other, and it does sound like there is a hell of a lot of communicating that's going to happen before you settle in to a comfortable zone, what you expect in a triad, what you are and aren't willing to give.
I also don't know that I'd say now you're their girlfriend. Have you considered dating other people, or being open to it until you are able to have either a sexual relationship with her, or a fully sexual relationship with either of them solo (sorry if I missed this, haven't had my coffee yet)? Have you told them if you want to be able to have one on one sex? If so are they working towards that goal or hedging about how they feel about that?
Good luck! I am glad you have a good friendship with her, I hope that makes it easier to keep making yourself vulnerable and speaking up about what is on your mind.
Happiness will never come to those who fail to appreciate what they already have.
Last edited by Anneintherain; 08-20-2011 at 09:37 PM.