What Does Bleeding And Low HCG Levels Indicate?

hey im 6 weeks and 3 days pregnant....I had my tubes tied 9 yrs age after my last child...went for an ultrasound Wednesday and they couldn t find my baby and said everything looks fine but they don t see a baby my hcg levels was 1460 and today they are 1680 they saying it should have doubled and this is a sign of an ectopic pregnancy...im not having pain but I am bleeding but they are saying its for them doing my pelvic exam but I started bleeding Wednesday right before my appt...so my question is where can my baby be at and y they cant see the sac nor a baby anywhere at all?