Small gestational sac!!

Megan • 4 yr old little girl, 2 MCs and now expecting again. Due Oct 7, 2016
Please help. I've goggled online everything there is to know about small gestational sac and it's so confusing and scary. I'm currently 7w 0d pregnant. I started having cramping and R sided pain. Was seen at OB and hcg and ultrasound were done as she was concerned about possible ectopic pregnancy. My hcg numbers are slow to rise and not doubling every 48 hours. The ultrasound showed a gestational sac at 4w5d (at the time I was 5w6d) so about a week behind. Nothing was seen in the sac. Fast forward to 4 days later I had a follow up ultrasound that magically showed a 6w 0d baby and a heart beat!!! However the sac was small. Very small. Ultrasound tech was very concerned. However the OB doc didn't seem as concerned about it. I'm now spotting pink blood and also some dark old blood. I'm already on progesterone suppositories and a baby aspirin because of other fertility issues. So my big question is...anyone else with a small gestational sac with successful outcomes or at least more knowledge then what I've been given by the dr. I'm so scared. My last 2 pregnancies were miscarriges. Any advice would be greatly appreciated!!