Can't help but be nervous (long story, but I need advice)

I received the news I was pregnant last Tuesday 4/12. I had absolutely no idea I was pregnant, due to not having a period in a year and having PCOS(polycystic ovarian syndrome). I was always told I wasn't going to be able to have babies. I went in for my first ultrasound 4/14 and the ultrasound tech said that she couldn't find a fetal pole or heartbeat, but she could find a sac and saw (what she told me) was a baby! The sac measured to be 6weeks 2days-GREAT! Then I stayed home the next day from work due to Nausea(4/15). And I get a call from the clinic saying that the radiologist didn't like the pictures because they weren't clear enough, and to go to a different clinic with a different machine and ultrasound tech. On that day(4/15) I had blood beta HGC testing done and went to see my OB/GYN. I spoke with my OB and she said that it could be a possible miscarriage, to prepare myself(because they couldn't find a heartbeat or fetal pole). After the ultrasound(4/15) they wanted me to wait to speak with the doctor on call about what the radiologist had found. He had found that I was measuring at 6weeks 2 days, and that he wanted me to have beta HCG testing done 48 hours later and that if it was a strong healthy baby, my levels would double. 
I went to get HCG testing 48 hours later and the results came back Monday (4/18) and here we my results- 
(4/15) 30,250
(4/17) 38,605
(I was told that after your HCG is over 6,000 it takes longer to double)
So I got a call back from my OB nurse, and she said that the numbers were troubling because they were supposed to double. But my OB Wanted me to go back for an ultrasound 7-10 days after to make sure what our next steps will be. Now I have an ultrasound appt on Monday (4/25) and I will be 7 weeks 4 days. And if there is in fact a baby I should be able to get a heartbeat and fetal pole, correct??
I have NOT had any bleeding or cramping. Yet one of my major symptoms(the reason I went in to have a doctors appointment and got the pregnancy test done) have deflated(sensitive breasts). But others have increased - nausea, fatigue and sore nipples! 
Have anything along these sorts happened to you or anyone you know? Does anyone believe that there is any hope left for my baby? I'm just so sick and losing sleep over not knowing. Prayers and advice are always appreciated!! 
Thank you everyone!