33+2, measuring small

Went for an US today, baby measuring small about 3.5lb, head/belly/leg all measuring about same. I have been gaining weight, my bump has been growing, her Heart rate is normal, everything had seemed to be fine . They are sending me to MFM for a level 2. I had previous scan last month after getting Lyme disease and everything was fine. I did have super stressful week at work and haven’t been eating as well as I should but this is just one week out of the whole pregnancy. Just worried and wondering if anyone is in the same boat.

Btw I am 4 ft 11, about 120lb, started at 105lb but lost weight during 1st trimester. My SO is 5 ft 4... but we were both big babies when we were born 😩