Irregular Periods & Possible Pregnancy: What to Do?

Question
Am I being paranoid?  I am an endurance athlete with irregular menstrual cycle (8.5 weeks, 30 days, 3 months between periods sometimes).  This year I have both decreased my intense training and have been having unprotected intercourse with my husband and now suspect that I may be pregnant, although two home pregnancy tests have been negative (tests taken May 2nd and May 8th).  I last had a period April 5 (before that it was February 5th, 2005, then November 2004).
I know that my levels of female hormones are orders of magnitude LOWER than "nonathletes" or "normal" women, so I don't know if the home pregnancy tests either 1. work for me or 2. were taken too soon?

I suspect I am pregnant because I am VERY sensitive to hormonal changes and can usually tell when my cycle will arrive based on "PMS" symptoms.  I started having PMS symptoms last Sunday May 1st and I keep thinking I'll have my period any minute now...but this has been going on for 8 days already.  I feel slightly bloated, full in the abdomen and at times EXTREMELY exhausted and light headed.  I have never been pregnant, so I don't know if this is me being paranoid.

Should I have a blood test taken by my doctor to confirm?  Please advise.

thanks.

Answer
If you had a period on April 5, then you could not have conceived prior to that. The earliest that you could have ovujlated, then, would have been April 18 (if your cycle was regular). If you did conceive on April 18, the earliest that a pregnancy test would show a positive result would be 14-21 days later or between May 2-9. I would repeat the test on May 9. If you still have any doubts, take two blood tests for pregnancy (Beta HCG) 48 hours apart. If it is a viable pregnancy there will be a doubling of the results in 48 hours. If it is a miscarriage, there is a halving of the results in 48 hours. If you were never pregnant, the value will remain at less than 5. Being an athelete or runner may cause you to have irregular cycles or lengthen your cycle, but it does not cause a pregnancy test to be inaccurate. Don't worry.