Baby fell off counter...i feel terrible?

Ok, I was babysitting last night and while I was cleaning up in the kitchen, I had the 16 month old baby girl sitting up on the counter. I was holding her up by her stomach while she was munching on a cookie. I glanced away from her for a split second and she fell off the counter, about 2 feet. I think I got her before she hit her head, but she cried for about 20 minutes, then seemed fine, just kinda scared. I tried to call her parents immediately, but they got rid of their home phone and didn't tell me, so I had no way of calling anyone. Plus, I was in the middle of nowhere with no neighbors in sight. She was awake for about 2 more hours, playing like she normally does, then I put her to bed, checking on her every few minutes to make sure she was ok. I checked for bruises or bumps when I changed her diaper, but I saw nothing. When the parents came home, I told them what had happened and they seemed fine, but felt awful about leaving me without a phone. I don't know if it didn't seem to bother them because they didn't actually see her fall of the counter or what, but I'm still really shook up about this. I can't stop picturing her falling and thinking about how bad it could have been, if she had gotten hurt and I had had no phone. I barely slept last night thinking about all this. I feel like I'm a terrible babysitter now and I don't know if I'll ever be able to babysit again. :(