Preggers in Bangkok, Hospital Info...

Hello! Although I feel much better reading that other women are bored, can no longer shave without help, and are playing it by ear while overseas- I still have many questions!!=) Thailand is more advanced than I expected, however, I am still concerned with the quality of care in local hospitals (especially because this is my first child.) I have been going to Paolo Hospital in Bangkok and really like the maternity unit, however, I am concerned because I am 20 weeks along and my doctor would not do a sonogram so that we could find out the sex of Baby. Has anyone else had this problem? My better half, although anxious to find out, deems this issue as beyond his expertise and my family says that North America standards show 18 weeks... then I read on here that some people are finding out at 12!! Please help!!