It's always good if you know for sure what you and your bf are ok with now. If that is a shared partner go with it. It's not the easiest thing to find but it will get you talking more and talking is important. Explore where your jealousies are coming from. Look for the root cause and see what you can do about addressing it.
Also there isn't any rush to move a new partner in. It might be an eventual goal but wait until the NRE has worn off before you even think of doing it. Also before you do anything as big as all moving in together there has to be a lot of talking about expectations and boundaries with all of you.
A lot of us started out unicorn hunting. It really isn't unusual at all. Some have even had it work for them. Please don't get sexually involved with someone your partner is interested in just to make that happen though if you don't feel the attraction. In the long run poly isn't just about getting your jollies or fulfilling your partners fantasies of two women.
Everything will be ok in the end. If it's not ok it's not the end.