Bbhoover, I'm thinking good thoughts for you. As I recall, your betas were really good, so there's every reason to expect a great u/s. Nonetheless, I empathize with your anxiety. I'm 14 weeks today, and when we had our first u/s (6w2d) I was having some spotting and cramping. I was SO scared we were losing it, because the only other time I was pg, we found out it was ectopic at that first u/s. My relief was indescribable this time around when we learned that everything was fine and even saw the HB (which you can't always see that early, so don't worry!).
I'll say this too: even at the next u/s, at 8 weeks, I was so nervous as we went into the clinic that I was practically in tears. I have felt much better since we "graduated" from the RE to a regular OB. As much as I love all the staff at the RE's clinic, I came to associate that place with bad news and "things being wrong."
Please take it easy, and let us know how things go on Friday.