Long story short I had a very faint positive on a frer Saturday afternoon. I then had some bleeding which now I think could have been implantation (although somewhat belated.) The bleeding had practically stopped so it only lasted 2 days and by half of that it was just leftover brown stuff.
Today I took another frer with fmu and there was still a faint line but it was darker than the Saturday one! With this one, I could see it without squinting.
Now I do have a doctors appointment on Thursday because of the bleeding and he told me that if the tests are still showing positive then I'll have an early scan either Friday or Monday. I know that realistically a line is a line no matter how dark, but I see so many people get such dark lines that I feel a bit worried. 
Do I keep on testing until Thursday or should I save my last frer for the morning before the doctors? Or do I not test at all anymore since I did already get my positive and I know that hcg levels fluctuate all the time and take different times to rise for different women.