Mixed Signals... Advice?

So I am now 11 days late (my period is like CLOCKWORK plus or minus one day for years), I'm having strange, vivid dreams at least once a night, craving hot dogs like they're the last food on earth, and food so spicy that unless it makes me sweat, I'm not satisfied. I'm also exhausted constantly. BF and I also had a condom mishap last month, but we don't remember the exact date. I've taken three tests, all say negative. Could my diet (high protien, low carb, been doing this for about a year) or vitamin supplements be affecting the results of the test? Could there be a problem with my possible pregnancy if my body isn't producing enough hormone to trigger the second line on the stick? I just want to have something to work with when/if I do end up going to the dr. for this. THANKS!!