2 Different Due Dates

Based on my LMP I should be 7 weeks exact today, but yesterday baby was measuring 6 weeks exact. Crown to rump was 3.3mm and heartbeat was 102.

My chart also says my uterus has a size and date discrepancy. I didn't know my LMP until after my ultrasound yesterday when my daughter's teacher actually reminded me what day it started 😂

Should I go off my lmp or my ultrasound?