You sound like me, I have three kids, stay at home with them, and have very few friends. Have you tried meetup.com, church, library? Are any of your children school age? If so, maybe join the parent teacher meetings?
I've made many good friends through the moms club... its nice because you get a calendar each month of stuff to do. I highly recommend you check out your local chapter. It helped my son and I get out of the house when he was little. He's in kindergarten now, so I keep busy with school stuff. I wish you happiness and joy with your little one.