No sac No baby

Am supposed to be 6-7 weeks today but went for an ultrasound and no baby no sac. Am so hurt right now. I have a follow up ultrasound in two weeks I bled for 5 days before finding out I was pregnant and been spotting pink everyday since then, my doctor checked and monitor my HCG for 2 weeks tho its been rising but not doubling, started at

77

311

524

639

923

1318

rising 42-44% in 48hrs. I got home after the ultrasound and took another test and its positive even with drinking a whole bottle of water 2 hrs ago. Am just down and confused