Talk to Gynecologist on Bpd Larger Then Actual Week

My problem is that I m 30w 6 days pregnant . Last menstrual was on 17 may till 23 . My doctor told me yesterday that your baby is looking larger then actual time. Then I did anomaly and in that the told me head is just looking 2 weeks larger then actual . My precnancy was very smooth from the start no one said any thing and I did anomaly at 6 month they said every thing is ok. So know why this happen ?? Is it showing any abnormality ??? I m worried about it. Please guide me. They told for gtt test as well.