Low Fetal Fraction TWICE

Has anyone else gotten a low fetal fraction result on their Natera test TWO TIMES? They told me it’s an increased chance of Trisomies when you have repeated low results. I tested at 11 weeks 5 days with 2.4% FF the first time and 15 weeks 3 days the second time with a 2.5% FF. I went back for the NIPT screening a 3rd time but not hopeful my fetal fraction has increased much above the threshold in the last 3 weeks. I should have just declined it like I did with my first baby. ☹️