Measurements

I volunteered at Owen’s college for an ultrasound so they could train their students. There were real doctors there in the room as well. She checked the measurements and she said that my babies stomach was a little bigger than normal and said I was measuring 33 weeks instead of 30 weeks. I called my doctor because I’m concerned about his belly. She just told me she really can’t do anything about it and that my records from a couple weeks ago were fine. Can’t things change though? Why won’t she get me in to see me? I called other doctor offices and hospitals but only my OB can do anything. She made it seem like it was nothing. I’m worried and they won’t check me. What do I do??