11 weeks 2 days today :)

Going to do a harmony test at next doctors appointment next Thursday because I had a miscarriage last year and to make sure everything is okay because for the past 4 days been bleeding off and on some not a lot but enough to be knowing it's not right. Doctor said it's breakthrough bleeding and that they wanna do this test to test for chromosomal abnormalities and Down syndrome and others. Any thoughts on this or has anyone went through this before ? Thank you :)