It's a tricky situation! I'm sorry you didn't feel the group were welcoming.
As a long-term home educator who has gone to lots of groups and is a bit shy myself, I am often on the other side of it, trying to figure out whether the new family want to talk or would rather take their time to get used to the new environment first. I want to make them welcome but not push myself on them. I'm conscious of the fact that some of the new kids will have anxiety and or autism, for example, and may not want some strange woman invading their space. I probably hang back too much, usually assuming that a quick smile and wave will assure them that I'm happy to talk if they want to come over. So maybe the others at the group felt the same as you?
There are also some parents (not including me) who have a lot on their plates and leave the welcoming of newcomers to others. They may be so busy watching their own child for signs of impending crisis that they have no mental energy for anything else, or may have had so little sleep the previous night that they don't even know you're there.
I know that doesn't make it any easier for you though! A few ideas:
Would you want to meet up with one family individually so you will already know someone next time you go to the group?
Would you feel brave enough to say (on Facebook or wherever people in your area communicate) that you plan to come along to the group tomorrow and you're a bit nervous and hope people will look out for you? I know that is hard, but then they will know that you do want them to come talk to you.
Is there a meeting with an activity so there is a focus, giving everyone something to talk about and allowing you to absorb yourself in the activity whenever you are feeling a little awkward? For example, we have ice skating where it's possible to skate round without having to talk to people, and then gradually over a number of sessions you'll get to know others there. I always recommend that for nervous people because it may feel like there is less pressure on.