Nipts Test

I had to take the Nipts testing twice. The first time before the testing I was told that if it was one boy it could possibly be a girl as well in there. They couldn’t be sure if it was two boys or one boy/one girl. When the results car back I was told there wasn’t enough fetal dna. I took the test again and was told it was 99.9% boys. The test was done a week apart. The next week I had an ultrasound the doctor said she could confirm it was one boy for sure. I am 17 weeks this week has anyone else have this happen to them or heard of it??