E.W.
We didn't really have any kids close to my daughters age in our family when she had her 1st birthday. We ended up just having everyone over and celebrating. We ate and socialized and had a great time. Really the first birthday is about the cake and watching the baby open his presents. One thing we did do was get a picture of my daughter and put it in one of the signing mats (you know for graduations and weddings) and had people sign and leave some words of wisdom for her. I hung the picture on her wall, she is now three and has me read her what people wrote all of the time =) She knows she's loved!
If you still need invitations I would be happy to help www.WorksofaWink.com