Yes, you need to clarify some of the info you gave…but even without that info, as Debra said, you should be strip testing your pup. There's no need to have your vet do any tests on her at this time BUT, you should be sending in the swab to find out what the linked marker test says. Regardless of what it does say, you should still strip test, but at least you'll have a better idea.
I started strip testing Apache right after he came back as Probably Affected, which was a month before his 2nd birthday. I strip tested him once a week at first and then when he hit 3 I did it weekly but did it a few days in a row at different times. When I did catch him spilling, just last month, he was spilling in the morning and early afternoon but not later in the afternoon or in the evening. At first I thought I was seeing things or that I somehow contaminated the strip. I had my husband come out and watch the second time..it changed again. Then I went and peed on one and it didn't change, so I knew then it wasn't that the strips were bad and I got him into the vet for all his tests.
They will spill sporadically at first which is why it's best to test a few days in a row and at different times of the day.
I have to admit to becoming a little lax with testing Cheyenne, who is a probable carrier, but since hearing of those that came back as carriers and are now affected, I've started testing her weekly now too.