By lmp i am 7w4d today. u/s 2 weeks ago told me turning 5w. only sac, baby barely visible. today, fetal pole and hb but baby measuring 5w6d. problem?

First trimester date: Depends on what the heart rate is. Assuming a normal heart rate, it is likely just that the ultrasound is more accurate at dating your pregnancy. Dating by LMP assumes a 28 day cycle with ovulation on day 14. Not all women have that cycle interval, making first trimester ultrasound more accurate in most cases.

Very early US dating: Not as good as us between 7-13 weeks. Measuring the fetal length (called a crown rump measurement) is the most accurate. The good news is interval growth, including a fetal pole with cardiac activity. Another followup us in 3-5 weeks could confirm additional interval growth and measure the crown-rump distance to re-evaluate dates.