Welcome to our forum.
It might be worth pointing out that some poly relationships have more than one primary relationship within them. So in theory at least, you could start out in a secondary relationship, and it could evolve into a primary (one might say co-primary) relationship.
I imagine it must suck to go home alone when the person(s) you were with has someone to go home to. I am fortunate, in that I am in a V where we all live together. But we had to get through some rocky years to make that work.
In any case, I'm glad you're on our site, and I hope that the something-more you are missing will come to you with patience and time.
Love means never having to say, "Put down that meat cleaver!"