First of all, take a deep breath and don't stress yourself out too much!
I'd have to say "ditto" to what everyone else has said. Make sure your little one is getting the required care before, during, and after. Make sure to ask questions and make sure to ask the right questions. If you want to you can search through the forums and there are a lot of great threads that cover just what things you need to worry about.
Zoë got spayed a week ago yesterday. I was sooooooooo nervous. She went to the vet at 8am and was out of surgery by 10am. Our vet is a 24/7 emergency vet, so there would have been someone there but she came home at 4pm. Her stitches were internal so we don't have to do a follow up. The day we picked her up she was a bit out of it. She was 80% normal the next day (though she really needed her pain meds that day), and by the next day she was completely herself. Now she's totally back to normal, besides having a few scabs left. It was a bigger challenge getting her to stay still and calm (to not hurt herself) than her recovering!
She was trying to run around and climb the stairs and just didn't understand why we were stopping her. All she wanted to do was play.
You're the expert on your Bella. Just keep an eye on her and as long as you're keeping her best interests in heart you'll be doing the right thing!
-Vicky and Zoë