beta levels after fet

Last Thursday I got my beta results back and it showed I was pregnant at 72, I went back Saturday and it was 157, I went back again today and my doctor called and said my level was 1954, and I asked if that was normal and she said it's a little low and that she would like me to come in for ultrasound and another blood test in the morning... I'm freaking out!! I'm so scared that this pregnancy isn't going to be successful... anyone have the same issue or any advice...