Prenatal screening/genetic counseling

I am 17w2d. This is my 2nd pregnancy. I had my 2nd trimester prenatal screening last week and results came back positive for neuro tube defect. Now I have genetic counseling and ultrasound next week. I know I should not be worried but this type of news makes me nervous. I've read online that other mothers have been diagnosed with false positive. Have any of you been through or are going through this? I really need someone to talk to. Just really worried about my baby.