Babyp17 - Not sure how early they can HEAR a hb, but they can normally locate it via transvaginal u/s by sometime on week 6. We saw ours at 6+2 flickering away on a transvaginal scan. Didn't get to hear it that early though.
Ethanandella - ok, here's the thing: it can be nothing to worry about and you may see your baby and hb in a subsequent scan, or it could be a blighted ovum. With a blighted ovum the sac develops and HcG rises normally as your body thinks it's pregnant, but no baby develops and it's basically a non viable pregnancy. I had that, but we didn't confirm it for sure until mid-way through week 8. Given that you are still on week 6, unfortunately you need to wait it out and see what happens, as it could go either way at this point. Sometimes it takes longer than usual to find a fetal pole on a scan and baby is still fine and healthy. Love that your doctor didn't try to scare you. Do you happen to have a tipped/retroverted uterus by any chance? Women with a retroverted uterus sometimes don't see their baby on scan until much later, sometimes not until week 8/9. For now it's a waiting game for you. Good luck, hopefully your little one is just hiding!