Couldn't see the spine? Advice PLEASE

Hannah🐙 • 20. Mommy to a little boy Watson since 10/06/18.

I had my 22 week anatomy scan just last week, and my doctor addresses that the ultra sound tech wasn't able to get a good measurement of my sons spine, but he didn't explain why?? Like if the baby was in just a bad position?? Anyone else have this experience? I'm very scared. This is my first baby.😔😔 Advice Please