Jan There have been some really great suggestions here.
I just thought I would drop another few cents worth, yesterday, after 4 or so months of mums group I got a call from one of the mums in my group to go and have a coffee, totally random, never happened before, we have not really spoken much, anyway we spent a couple of hours walking and talking about things mostly entirely unrelated to the bubs and discovered we have quite a lot in common! She interestingly commented that she had been lonely but very shy about contributing at the group as she found the whole group situation very overwhelming.
So you are not alone. Keep at it.
And most importantly good on you and THANK YOU for being open and verbalising what so many of us are/have been thinking! It is very nice to realise that feeling this way is normal. Your post has given rise to some great discussion - women helping women - YEAH!
Good luck!