What are other possible things that could be wrong with my body if I have pregnancy symptoms?

My period is late. I normally have pretty short cycles, about 24 days. Its been 27 days since my last period. I have been feeling VERY bloated and tired lately. And I have a dull stretching pain in my abdomen. I'm going to the bathroom frequently and have sore nipples. AND im constipated! Normally I have no PMS signs whatsoever so when i googled these symptoms all that keeps coming up is pregnancy. My bf and I use the withdrawal method so I shouldnt be preg. but something is def. wrong. ANYWAY I did a test today and got a negative.

I'm trying to figure out what else could be wrong with me. I don't want to be preg. seeing as I don't have health insurance, but it would be better than finding out I'm dying from appendicitis or something. I cant see a doctor until next month when my new health insurance becomes active.