Thanks for the advise girls! I tried calling her but she didn't pick up. So I sent her an email with my apologies and let her know that my son is adjusting to me giving her son (who is 13 months) all this attention. I also sent pictures that I had taken of her son while he was here and in almost all the pictures he has a big smile on his face while he's playing with my kids. I feel like her decision has been made since she decided not to pick up her phone. She is a first time mom and on our interview, she told me that no one other than the parents have taken care of the kid. And she only sent her son to those indoor playgrounds once and her son started crying, and she blamed the playground supervisor for making him cry.
It might just be for the best, because if she does decide to send her kid back, I know she would be watching me and my kids like a hawk. Funny thing was that when she came to pick her son up, the kids were playing happily together. And she ran to her son and picked him up and didn't seem like she wanted to stick around much longer.
I'm so glad that I posted on this forum, I feel a little better. We are going out to put up flyers on mailboxes again. Keeping my fingers crossed to find a good trusting family this time.