I am talking to the "Mr," it seems? We do have a rule in our Guidelines here that a couple may not share an account. If you insist though, please state who you are when you post. It really puts other members at a disadvantage to not know. But the fact that you started a shared account and used the term "we" in your OP instead of "I" shows how couple-centric you are.
Swinger to Poly
We got into swinging because the Mr. was interested in a 3some and the Mrs. was bi curious. 10 years later we have found swinging is mostly couples and one of us always feels left out. For the Mr., he doesn't like losing his wife in the midst of playing and for the Mrs., she doesn't enjoy watching the Mr. We are very much in love and we prefer being together in a 3 way connection.
Our best experience has always been with a bisexual girl but that is very hard to find.
We want to find an exclusive bisexual girlfriend instead of swinging...
We thought about gay clubs but worried that might attract the wrong type. We tried meeting single vanilla girls but that doesn't work.
Do we try monogamous sites with girl looking for girl?
Do we try dating separately and be honest until one of us finds a good match to bring home?
I see why you want to get out of swinging. You want a bi woman who will give you both sexual attention in 3way sex sessions. You don't want another guy around because the nasty swinger dudes have a habit of taking off their condoms partway through having sex (really?? What the fuck, swinger dudes?). You don't want a STD.
It seems you are not as polyAMORous as some couples that come here with questions (or to put Personals ads in our forum for that). You are polySEXUAL. You really get off on being in FMF (or is it really FFM?) 3somes. You want someone to commit to you both for SEX and not much else beyond perhaps casual socializing? You are wondering where all the hot bi babes who want sex with a male and a female simultaneously are?
Women are notorious for being picky. I am hella picky. We don't just drop our drawers for any man (or woman) and are even less likely to drop our drawers for a committed couple, unless we are really drunk. Another poster upthread took a lot of time to list the reasons why.
It's really an almost impossible quest. I'm sorry. It just is. Your questions about how to find this HBB are good ones. There is no answer though.
My best suggestion, other than being constantly searching, constantly rejected, is to look at your joined at the hip attitude and see about becoming just a little more independent (if you desire extramarital sex really badly). There is a lot to be said for dating independently, but it depends on working through those jealousy feelings, which can be done.