I wouldn't rely on an ultrasound at 12 weeks, unless you're getting the blood test done that tells you?
You find out the sex at 12 weeks? Doctors here won't even check until 20 weeks lol. At 12 weeks it definitely won't be a definite guess but I hope you get to find out! Waiting is a drag lol And they couldn't see at 20 weeks for me. I had to wait until 37 weeks! XD