3 month old baby head circumference

my daughter is exactly 12weeks and 4days..at birth her head circumference was 36cm, at 8w appointment it was 38.5 and today it measured 38.7, only 2millimeter growth😰 doctor said we will keep monitoring and since she has achieved most of the milestones of this age there is no need of a immediate MRI scan( she was 3.6kg at birth and now 4.9) she was a big baby at birth and now overall a small baby,she is exclusively formula fed, crying always (dr says colic)…mammas out here do u have any similar stories to share? is this normal?