High Inhibin A. Screen positive for T21.

I had NT NB scan on 20/11/2020 at 13weeks 1 day and it was normal. Since my doctor miscalculated the week for dual marker test, I took a quadruple marker test on 18/12/2020 at 17 weeks and it showed inhibin a level at 559.9 pg/ml. Since I did not have an ultrasound before taking the quadruple test therefore the pathology corelated it with the 13 week scan. Just to be sure, I contacted another lab to take another quadruple test and they said that the earlier test results could be wrong since the ultrasound used for correlation was almost a month old and I was asked to get another ultrasound and have the results recalculated. So I took another ultrasound on 19/12/2020 and all fetal parameters are normal and baby is measuring correctly. Please guide as to how should I interpret all this and should I be worried? My age is 31 years and this is my first pregnancy. There is no medical history on either side of the family. Thanks in advance