First off, I don't think you are doing anything wrong I was in a similar situation with a playgroup I attended with my boys. There were close friendships within the group (only small) already and so I was on the outer from the get go. After feeling like you for awhile I did make an effort. Although I started to enjoy playgroup more, it still felt one sided and I still wasn't being included in anything the other girls organised on weekends etc. The deal breaker for me was that they would pop a status on FB about movie nights and dinners out or even just getting the kids together, and tag each other. I realised that if these women were comfortable enough to leave one person out and do it in a really obvious way, why would I want to be friends with people like that? So I found another playgroup who are very inclusive, not just at playgroup but anything organised outside the playgroup too.