I feel the same exact way as you do. And nothing changed til my daughter hit kindergarten. I look extremely young for my age and I swear other's thought they were to good to talk to me at times. I started volunteering alot at my daughters school and met so many moms who like me were bored at home and needed friends, then my daughter is in soccer, and all sorts of things and we all get bored on the sidelines and chitter chatter. So hopefully when your little one starts school it will get better.
In the meantime, just walk up to a parent at the park and make a excuse to ask a question. example "Excuse me I love your little girls shoes, where did you get them?" Usually it will lead into some kind of conversation. Other mom's love compliments about their kids. Make something up if you have to. Approach the mom who is also alone like you and isn't busy with a cell phone or distracted with something. I stay away from the clicks of mom's I figure they're alreay busy.
I come off snobbish too, most of the time I'm only concerned about my daughter especially when it came to preschool that was horrible. All the parents knew eachother before hand, carpooled, and never gave me the time of day. Then because their children all knew eachother outside of preschool they weren't real interested in making new friends so they could care less about my daughter. The kids always made plans for after preschool and carpooled home. I felt like we so didn't fit in. I taught my very social daughter to go after the kids who don't have friends the loners. She did just that. She became very good friends with a little girl who's family is immigrated from Mexico and their was a bit of a language barrier but they are even in kindergarten together now and are real good friends.
I think things will get better for you as your daughter get's older and more involved with things. My best friend also doesn't have any children so it makes things different.