6 weeks LPM but 5 weeks on ultrasound.

As per my LPM I should be 6 weeks pregnant but through TVS today the doctor said I am 5 weeks pregnant and I don't have to worry or get scared. They gave HUCOG HP 5000 injection (twice) and asked me to take it again after a week. I am also prescribed susten sr 300, stafit, moringa oleifera syrup for the next 10 days. Next scan on 8th august. After TVS, they took blood test and they said everything is fine and prescribed all these but unfortunately the doctor had to leave so I couldnt discuss about this. I want to know if this has risks of miscarriage or preterm because I am stressed and I was extensively researching all the prescribed tablet components and I kepts seeing these words repeatedly. Please advice. Is this common or should I be worried? LMP- 11th june.