Could I be pregnant and the doc's tests are wrong?

[Lindsey]

My period is over a week late. I think we conceived on july 17th or the following week. Don't know anything about conceiving..ain't in the market. I'm a corporate sales woman trying to climb the corporate chain and get an mba and my husband is working on his at ucla. Anyways, I took four pregnancy tests at home, they had faint blue positive lines on Friday, August 13th. Went to the doc on August 17th. I am on the pill but I take Topamax which decreases it's effectiveness. I feel sick to my stomach at times and smell things intensely (especially in the car with the a/c on-ick). I'm starting to feel some cramps (like menstrual cramps). I don't know. All doc tests were negative. I had a cup of coffee before going to the doc. Could that have an effect on the urine test? I just dread going back to see my doc. I saw the NP and she tried to tell me I didn't know how to use the HPT rather than listen to me and how I'm feeling, what meds I'm on, etc (I brought all the tests with me too) . I made an appt with my doc this time. The thing that worries me is I FEEL like something is wrong and if it is a pregnancy, I'm on anti-sezuire meds, I need to work with my docs fast. What do you think ladies? I guess I'd be a little past 30-32 days???