So was suppose to have my anatomy scan this morning

I was suppose to have my scan this morning and they wouldn't do it cause I was only 16 weeks and 5 days I'm really confused cause every find out so early and they told me they couldn't do it till I was 20 weeks and I'm really upset cause I don't know what I'm having and I just wanna know and they screwed up cause the doctor I saw kept telling me she thought I was a week ahead I'm like what so I took today off cause u guys screwed up and this my fault