I can sympathize. Besides working with a lot of women around my age (they all seemed to either be raising kids or getting married and planning them), I live in a subdivision that is overrun with children (most homes have at least 3). Of course, that's why we moved here, but when it took us so long to have a family, it became a bit lonely. Like you, because I worked outside the home (a lot, trying to save for adoption), the women and their kids formed their little groups. Through the children, neighbors bonded and DH and I sat by the side. Last year, I tried to get out there and meet people with little success. This year, I am breaking into the mommy groups if it is the last thing I do!
It's hard to feel left out, but, hopefully, soon enough you, too, will be able to join in.