I went to see the doctor in 法國hospital once, I asked the doctor if I need to go to private doctors to do ultrasound regularly to check if the size of the baby is normal. (BK mothers mentioned government hospital seldom do ultrasound)
Because before when I went to see him, I found (in some web sites) some mothers find their babies sizes are a few weeks over or under the normal size, the whole body or particlular body parts.
The doctor said actually there are quite a big tolerance for the size of the babies, so there's no actual needs to check the body size regularly.
If what he said is right, you don't need to worry.
But he didn't mention actually how many weeks is the acceptable tolerance, maybe it depends.
Maybe the doctors of other BK mothers do have other comments.
I'm now 9mth and 肚 is in a small size like 7mth but the baby now got 5pds. However, my 胎水is not relatively less and doctor said that I need to have more rest.
I am now 8.5Mths, but looks like 7 months only. I saw 2 doctors, both of them said baby's size is average and 胎水 is enough wor. So, don't worry! Doctor said ok is alright la!