After my 5th step, I really felt that I belonged in AA. Then after sponsoring people for a while I really felt that I was a part of not just AA but of the human race.
The opening of "There is a Solution" talks about the fact that we are like ship wreck survivors. There is a sense of companionship because we have survived together. We all have the same problem. But it goes on to tell us that alone would not hold us together. What really binds us is the solution. In my experience the solution has not only made me feel a part of AA, but it has broken down the walls that have always prevented me from connecting with anyone. AA or not.
I suggest, as Sugarbear did, to schedule a 5th and continue the work. You're not alone! You can do it!