I found out at 17 weeks with mason and 18 weeks with Charlie. I went to the .er at 14 weeks and the tech said she thought baby maybe a boy but like daddy, baby wouldn't sit still. lol

we were lucky and found out at 16 weeks with our son. had to go to ER for pain and they checked on him and asked if I wanted to know the gender lol its a great feeling

I was 18 weeks when I found out. As long as your doctor has a good machine and the baby just isn't COMPLETELY covering you should be able to find out. Good luck!