How far in between ultrasound appointments??

Melissa💗 • Rainbow baby born in 2016, then another miracle born in 2018! 🙏🏼 Currently just found out pregnant with baby #3! Fingers crossed all is well! ❤️
Hi all! So today I am 13 + 4 and had my last u/s last week. But they didn't schedule me for my next one until almost the end of July when I'll be 18wks! That just seems sooooo far. Is it normal for u/s's to be so far apart? I had thought about also booking a private u/s sometime in between but read (of course online) that those places sometimes have heavily uv equipment since they're not medical... Any thoughts or help towards this would be very much appreciated!! Thank you 🙏🏼❤️