7 wk 1 day measuring 5 wk 4 day

Has anyone else experienced this? This is my fourth pregnancy. I've had a missed miscarriage and a d&c bc the baby died.... Even with my son who is now 10 I don't recall measuring small with him. I'm petite but I logged my period with an app so I'm positive of my lmp. I go back in three weeks for another ultrasound / sonogram. I'm just a little concerned because I'm considered a high risk pregnancy. Any. Advise or similar cases?