Baby measuring small at 33 weeks

♚NAS♚ • Born in South Africa.. happily married.. 2 baby boys under two years.
Okay so ive been to my appointment on the 4th of August and the doctor did a scan and said everything was fine with baby .. and thatbthe size was good .. so then i had another appointment on the 20th of August and I was seen by another doctor and she says to me that my baby is small by 2 weeks .. has anyone experienced this??? .. its really been bothering me.. she says there is still time to help baby grow by having enough protein and trying to always lay on my left side for better blood flow.. she asked me monitor babys movements and to come in at anytime if I feel something is wrong .. so I'm now confused as to how one doctor can say the size is good and one doctor says 2 weeks small.. please anyone who has experienced this or have any information at all will be a big help to calm my nerves .. not to mention that they are not even sure what baby I am.having .. one doctor says a boy .. another 2 said they don't know and then one says a girl .. they are driving me insane.