At My 20 Week Anatomy Scan, Our Doctor Said Our

At my 20 week anatomy scan, our doctor said our baby had an abnormal skull shape and sent us to a fetal medicine specialist. At our appt today (20 weeks and 2 days), the doctor said my baby's head is slightly lemon shaped, but that the cerebellum and ventricular spots in the brain were normal. Also, he could not see a spine lesion. He told us not to worry, but that is tough. What are the chances of her having spina bifida at this point? If she does, would it be very mild?