I went to my GP right away - I knew nothing about Lyme back then. It was, here's the doxy (3 weeks), you'll be fine. I believe 'they' feel it's not worth it testing early on while you're under treatment and I forget why really. The antibodies haven't had time to build up? That was 4 years ago. I went to a LLMD after the 1st round of doxy 'cause I still wasn't feeling right, and she prescribed another 3 weeks to make it 6. She did test me then - and tests came back negative. Was it too early then as well? I don't know.
Okay, I just went to Buhner's book and it does have to do with having 'measurable antibodies'. Again, it's complicated and many factors to consider. Do you have his book?
Did you take pix of the bull's eye(s?). I had the 'real' thing to show my GP, and then the pictures to show the two LLMDs.