What we should follow? EDD by last month of menstruation or EDD based on BPP ultrasound?

Hi! Based on my calendar of mestruation i am.36 weeks and 4days. Based on my last 3 ultrasound I am 38 weeks and 6days today. ( Had a monitoring ultrasound today also) Im currently taking Heragest and Isoxilan 3x a day due to high risk pregnancy and history of miscarriage plus myoma on my uterus. I am worried what if the baby wanted to go out early and im still taking heragest and isoxilan and it hinders the labor process? My OB told me.to take those meds up to 37 weeks.. pls advice. Thank you momshies...