30 weeks and low baby weight

Went to my high risk doctor yesterday for a 30 week growth scan due to my bicornuate uterus. At the end the doctor called me into his office to tell me my baby's weight is in the 35-40th percentile and the abdomen size is only in the 12th percentile. He said not too worry just yet and will see me in a few weeks to measure again, but I can't help but feel upset and scared for what this could mean to my baby. Anyone else have experience with this?