W12-W20 appointment? Too far apart?

Hi mommies. I’m currently in week 17 and my last appointment is week 12. At first i didn’t really think much when my gynea told me next appointment is 8 weeks later ( week 20) But some of my friends say theirs is 4 weeks apart. So I’m getting quite anxious as it has been so long. I dont know if anyone is same case like