My gynae's able to tell me my baby's gender when I was 16 weeks pregnant, but she was then only 70, 80% sure. Its only until my 20 weeks detailed scan that she was able to confirm that I'm having a boy when we clearly saw his teeny weeny. But having said that, you'll have to have your baby's cooperation, I have a friend who didn't know her baby's gender until her third trimester coz her baby's hands or legs are always covering up the area. Both my 16 and 20 weeks scan are done by my gynae, not by sonographer.
I do not have any nasal problem, but I've been having alot of phlegm, sometimes cough, since my pregnancy.