Baby’s belly measuring 90th %tile

Just had my growth scan at 33 weeks and my baby is measuring in the 65th percentile; however, his tummy is measuring 90th percentile. I am now tracking my glucose and on a strict diet as of today but i feel like the damage is done and I am worried no matter what I do he will be born with a big belly. I just feel like crying and a complete failure for letting him get that way, and thinking about how uncomfortable he probably is. Has anyone had this happen and their baby be born healthy and with a normal size tummy? As of right now my doctor is planning a c-section but waiting for another growth scan at 38 weeks to confirm.