Hi,
Welcome to the ehealthforum. I am glad to help you out. False negative results with urine for pregnancy tests have been reported.
Urine for pregnancy tests are not very specific and can be false negative also. I would suggest you to get a highly specific urine for pregnancy test like aimstrip test done or get your serum HCG levels estimated.
The serum test should help in ruling out the pregnancy.
There's a possibility that you might be having stones in the urinary tract. The stones can produce both the bleeding in the urine as well as the recurrent urinary infections.
Please get a CT scan of the kidneys, ureter and urinary bladder done to rule out the same after consulting your physician.
I sincerely hope that helps. Take care.