How do I know if the sitter declined my request or if the timer ran out?

I recently downloaded this app a couple days ago and I have no idea how it works. A woman agreed to watch my dog and told me that the request was pending my approval. The next morning, I got the automated "unfortunately so and so cannot accept your request." I messaged her twice afterwards and she never replied, and this was yesterday. Did a timer run out on the request because I did not approve it? Or did she just agree and then change her mind? I'm worried that I'll come across as pushy if I message her a third time or if I try to rebook.