At 16 weeks i was told it looked like a boy but to wait for my 20weeks scan to confirm (which is tomorrow) sometimes they can get a really good shot and tell but its alot clearer abit later on.
YES! No ultrasound is 100% but you can find out via ultrasound with very good accuracy as early as 14 weeks. I did at 15 weeks. It was very very obvious it was a boy. Some Drs don't feel comfortable saying untill 20 weeks, but it's very possible at 14-15 weeks.
I found out at about it 16 weeks with both pregnancies but you should have an anatomy scan around 18-22 weeks
I found out I was having a little girl at 16 weeks so it's not impossible.
No ultrasound is ever 100% guareented to tell you what the sex of the baby is, but you can find out what the baby is at that early. I found out just about 14 and a half weeks and again 2 and 4 weeks after that (I'm high risk so I have multiple ultrasounds) you can find out through a blood test, I've heard anyways
15 weeks is too early to make a good guess, but you'll get a special anatomy scan at around 20 weeks to make sure baby is growing all right and that's when they'll be able to have a better look at the gender for you. :) Probably not what you wanted to hear lol it's agony to wait! But any guesses right now won't be very guaranteed.