The doc says i have a Chemical pregnancy but my HCG levels say otherwise.?

I am 7 weeks 4 days pregnant. At 6 weeks, 1 day I had my 1st vaginal ultrasound. The doc not see anything. My HCG levels were 13,000. At 7 weeks, 1 day I had a 2nd ultrasound. My HCG levels were 22,000. The doc still did not see anything. NO yolk sac nothing. He said I have a chemical pregnancy. I also had a ultrasound by the radiologist and he seems to think it may be too soon and there is still hope. ANYONE ever come across this situation? I am confused because my HCG levels and body say I am pregnant. I have had no bleeding or cramping. My stomach is growing my hips are spreading and my boobs have increase two bra sizes already. I eat healthy and I walk or hike 3 to 4 times a week. So i know i am not getting fat from my diet. PLEASE HELP. I am so worried. Do i accept I am going to lose the baby or do I have hope? The doc said it could take 2 to 4 weeks before i start bleeding and actually have the miscarriage.