Unsure due date

Jessica • Blessed to be a wife and mother

Hello ladies...looking for any type of feed back. My last period was May 26 so according to that I should be 10 +5 how my doctor is saying I’m closer to 6+ 6. My levels were low in the beginning if I go by my period but they have been rising how they should be. I saw baby in a vaginal ultrasound but no heartbeat at 5+6 which is totally normal. I go back next week to hear a beat and see baby size. Anybody been in a similar situation? I’ve been spotting everyday since my missed period. Should I be worried about anything? My last two pregnancies were nothing like this.