Just depends your next appt isn't until about 6wks so, not your next appt, but your next @ 18-20wks when u find out the gender. That's the norm. But, depending on your insurance & ob you could have one sooner.
Depends on the doctor most only give 2-3 so probably not another ultrasound until 18-20 weeks for gender and maybe at the end on your pregnancy. They'll do more if you have complications. My doctor gives everyone one every time they go in.
i had one at 13 weeks (growth and measurements, nuchal cord etc) and one at 20 weeks (organ development and gender determination). Those are pretty standard, were you told you'd only have two? I'd guess if you only have one more it'll be sometime between 16-20 weeks.