I don't think blood tests would have a risk of miscarriage and if your result was 3-4 at the time the blood was collected then it was probably a chemical pregnancy and failing prior to the blood test already
I don't want to sound harsh I had a Chem too and feel it was just as important as my own living children
If there was a notable risk they would have a duty of care to advise you of it
But ultimately I guess you can only do what you feel your are comfortable with and if these tests are going to give you stress then waiting is really the only thing you can do eventually a baby is going to come out if you are pregnant