ER visit tonight

So I had a miscarriage 11months ago and am now pregnant. According to my LMP I should be 7wk3d but on ultrasound tonight at the ER it measured me at 6wk2d. Fetal heart tones was 135bpm and sack looked healthy. Has anyone else measured a little behind and still have healthy full term pregnancies?! Thanks I'm still a little nervous since I miscarried at 6wks when I should've been 9 the last time..😔