Help!!!!

So I went in to have my pregnancy confirmed. The pregnancy test came back positive, but the ultrasound came back clear. There was NO sac. According to my LMP I am 7 weeks pregnant, but I have a 37 day cycle. So, technically (according to the sonographer) I can't go by their wheel. But that's how they figured up my DD and when I got pregnant, on a 28 day cycle. So, she said I may be earlier in my pregnancy than I think I am.

Should I be worried? Just wait until my next appointment (2 weeks away)? Or what? I am totally freaking out! Has anyone else had this problem?