Even the oldest test strategies for testing are consider very reliable that far out.
But you would have to find out more about the test from the person who order it. Depending on the test, you either have to wait another 3 weeks or not have to wait at all.
There are some test e.g. 4th gen test that are conclusive at 4 weeks. PCR tests, also in that time or less.
Try to find out more and write back.
I seen Dr. HHH say 9 weeks is very reliable and your results should not change. However, on this forum, we tell you that you will get a conclusive result after 3 months. As for the type of test they use, you should ask them.