2nd pregnancy 13 years later

I had a miscarriage last year a day before my bday.. I found out last Monday that I was pregnant... my hcg levels are increasing but I had been spotting on and off all last week up to Monday... but the hcg levels aren't doubling like it supposed to.. I'm scared that I can have a miscarriage the day before Mother's Day... we are all excited for this baby.. oh and they did an ultrasound on Monday but didn't find anything... now today obgyn doctor says it can be an ectopic pregnancy.. where it's not in the uterus.. I'm scared