Genetic Testing?

I wanted to do the first trimester testing (blood work and NT Scan). But I can't get my insurance commit to quote me on the cost. I've heard horror stories of people ending up with $5K+ bills because the testing wasn't medically necessary. I'm 31. If I don't get it, I'm terrified something will actually be wrong. What are the actual chances of baby having a chromosomal disorder?? Can I skip this testing without feeling guilty??