lmp due date 2 weeks off?

Ashley • 31 married. beautiful 12 yearold, Handsome 6 year old. Adorable 6 month old and now 🤰🏽 👼🏽9/21 👼🏽02/22

my first ultrasound was yesterday and from my lpm i was supposed to be around 8 weeks 2 days. well the ultrasound says i am 6 weeks 3 days and there was a strong heartbeat of 143. im so confused this means i found out i was pregnant less then a week after i concieved!? there was a heart beat so im trying to have hope. but i feek like two weeks off isn't normal. any one else had this?