I am only four days late but I have exteme heart burn and I am exhausted. I have frequent urination and am very thristy, I am not diabetic, I checked my blood sugar already. I have taken two home pregnancy test one with morning urine and both are negative. They are the digital tests that say not pregnant... should I be worried about being pregnant?

It's a possibility... sometimes it can take awhile for the urine tests to pick up the hormone... can be several weeks even for some women, although usually it is much sooner. You might want to give it several more days and see what happens... your period might just be off this cycle.
If still no period, try another test at that time, or you can contact your doctor for a test in the office. Most will use a urine test in the office anyway, so you can ask first and see if a blood test might be possible for a more definitive answer.

Your symptoms of pregnancy shouldn't be showing up that fast.

Wait a few more days, then take a 2-pack hpt in the morning.

>>>>Your symptoms of pregnancy shouldn't be showing up that fast.

You'd be surprised how early many women "know" that they are pregnant. Many of the early signs will be similar to a period about to come on, so some women are feeling them even before the period is due. They especially notice them when they are trying to get pregnant as they are watching for any possible indication of success... :)

I understand the intuition that women "know" when they're pregnant... but heart burn, thirst, frequent urination... these occur later in the pregnancy.

SO many women have come in the clinic thinking that they're pregnant as their breasts are sore, they're constantly exhausted, etc... then once the test results come out, these "symptoms" disappear miraculously. The mind is a wonderful thing...

>>>>I understand the intuition that women "know" when they're pregnant... but heart burn, thirst, frequent urination... these occur later in the pregnancy.

Usually most symptoms do occur later... but it does vary from woman to woman. For some, the hormonal changes early in pregnancy will cause them to notice some symptoms in the first few weeks. Three that I have seen the most that early are the exhaustion, frequent urination, and very tender breasts... particularily nipple tenderness.