BlueCrane did I miss something where your doctor said you weren't pregnant because they line wasn't dark enough on your test?! 

A line is a line according to my doctor, who is also a relative and totally brilliant. Your doc sounds like a ninny.
Did she ask you to bring used pregnancy tests to an appointment? You know that a line from a BFP can fade entirely after an hour or two?
The result is only valid during the recommended time. It works both ways - BFPs that disappear still count as BFPs and ones that appear too late don't count.
Sorry you're having all this hassle :(
I feel the same way about continued testing post-BFP as I do about early testing - it just creates stress and hassle where you need to be trying to minimise it and enjoy TTC/being pregnant.
I used 2 Boots own for DD1 (had to do 2nd one just to be sure :o), and 1 for DD2.
That's a total combined test tally of 3 pregnancy tests for 2 babies. I've done 0 tests so far this time. There's no need for all this constant weeing on sticks and I'm surprised at a GP for encouraging it and stressing you out over the thickness of the line.
Anyway, I hope you're having a nice weekend enjoying the terrifying and exciting first few weeks after BFP :) :)