based on my own experience and my gfs' who were with Paul for their pregnancies, he usually doesn't get too concerned about the weight of babies. in fact, he doesn't usually do ultrasound scans unless the expectant parents want to see their babies or there is a medical reason or need to do so. when my hubby asked him a couple of times about our baby's estd birth weight (becos my tummy was clearly bigger this time than when i was expecting #1), Paul just smiled and said not to worry. my gfs also testified that they never told them about their babies' weight and some of them went on to deliver as heavy as 4.4kg babies naturally! perhaps it's his way of not worrying parents-to-be over something they could not really control.
i suggest that you discuss with Paul in greater details what his concerns for the weight of your baby are. i would think that it being a vbac, there would be some restrictions. for instance, i have heard Paul say before that labour induction for vbac is not possible because of the danger of rupturing due to the stronger contractions brought on by medical induction. you could ask him what you can do at this point in time regarding the weight of the baby to get a better chance at delivering naturally, what he as your obgyn can do to help you, as well as whether there is a maximum weight of baby to proceed with vbac or a threshold weight beyond which he would not recommend/support vbac.
all the best!!