Threatened miscarriage

I've been told this for weeks. To prepare to miscarry, that I'm progressing slow, numbers aren't doubling. We've seen a yolk sac and gestational sac, no baby yet. I'm confused because I haven't bleed, still have increased symptoms. The doc said it would be a chromosome issue and my body wouldn't rid of it. I go in tomorrow and obviously we are clinging to any hope. Anyone had this happen? And have a healthy baby?