Sac is measuring 2 weeks behind from LMP but doc cant see a fetal pole, yolk sac or heartbeat.?

Ok a few weeks ago I went to the doctor to confirm my pregnancy was in my uterus and not my fallopian tube, for I was at risk for a ectopic pregnancy. I shoukd have been 7 weeks from my LMP, my sac was measuring 5w4d.. He couldnt see a fetal pole or yolk sac or detect a heartbeat. So he drew some blood to check my hcg levels and had me come back in 5 days for another sonogram. When i returned for my follow up scan my sac was measuring 6 weeks exactly, but still couldnt see a fetal pole, yolk sac or heartbeat.. But kept informing me that my uterus is VERY tilted. My hcg levels were pretty high so he wanted to check them again. He sent me home called me the next day with the blood results and my levels were rising. But he told me since he didnt see anything he wasnt sure if this is going to be a successful pregnancy, but said hes not ready to do a dnc yet, so im basically just suppose to wait and see.. I personally think this doctor is a quack. So mabe a i just ovulated late in my cycle and everything just wasnt developed yet??? Has this happened to anyone?? Any advice on what I should do next??? I want to get a second opinion from another doctor but just want to see what others experiences has been. If my sace is measuring two weeks behind from my lmp then it should be measuring right about 8 weeks this week. Should I go ahead and make another appointment or wait until my sac should be measuring closer to 10 weeks. Thanx in advance.