Small then caught up

Hey just wondering if there are any other mommies out there who's little bean was measuring small at dating scan and then caught up during the anatomy scan. My little babe was measuring 3 days smaller than LMP at dating scan which made sense because I have longer cycles so ovulated later. Now my little guy is measuring right on with LMP. His head measurements is still 3 days behind but the rest of his measurements vary in sizes with an average calculation being spot on even with LMP.