C.,
You ARE being used, and there is nothing I dislike more than women and clicks. I thought we left that in middle school, but I encounter it often.
You seem very nice, and probably don't want to rock the boat. I think you need to call a meeting with the officers, and voice your concerns. Write it all down so you don't get flustered and upset. Tell them that you take the time to get speakers and if they are going to change your agenda without consulting you, change meetings without consulting you, then you are prepared to step down and let one of them take over.
You could say that it seems as if they really seem to have it under control and that you don't think they need you in this position. Tell them you could use your time more productively and thank them for the "honor" of this position, but "they" really don't need you. You'll need to decide if you want to stay with the group. If you do, you could end by saying you'll be looking forward to the next get together. If not, you could say it was nice getting to know you all and I wish your group the best. Bye!
I myself am not much of a playgroup mom. I am 45 with 2 older kids, and one that is 8. We make play-dates with one of her friends and go back and forth between the different kids houses. Or once in awhile we will have all of us parents and kids together. We just had a Chocopalooza where we brought everything chocolate, plus some healthy snacks, the moms hung out and gabbed, the kids played. More laid back, not so structured.
Well, I wish you the best and hope it all works out for you. Remember, all because you are the new kid in town, don't let people take advantage of you.
R.