Worrying, but not worrying. Anybody else??

Megan • My name is Megan Taggart. I live in Indiana and this is my 3rd pregnancy. I miscarried with my 2nd, so were praying that this one is a stickler!!
So, I'm 9wks 5days. At 7wks, I got my ultra sound and we were able to hear the babies heartbeat, but the tech said that I was measuring only 5wks 6days, which was fine. I kinda figured I was a week behind what the doc told me anyways. So also couldn't really get a good measurement because the baby was tucked in a corner. Well, today I had gone for my appointment and the doc tried to find the heartbeat, but he could'nt find it. He said it was normal that it was still alittle early to hear it, but it didn't really start worrying me until now. I'm not really worried because I still feel pregnant; tired, sore boobs, nausea, irritable, all classic pregnancy signs. Plus, I still feel pregnant. I guess I just want to know if anyone else has experienced this. Like I said, I'm worrying, but I'm not worrying.