Any advise?? Please

ka
If I have had 4 normal periods (on the pill) and have taken a few pregnancy test and they have came back all negative (including a hcg urine test done by the doctor and at the lab) 
Is there a chance I could still be pregnant?
I know that seems like a silly question but I know when you have your period on the pill it isn't really a proper period... 
I haven't felt right in myself for a few months and I'm stressing about it, I have been to a urologist for ongoing high white and red blood cell count and going to have a MRI and cystoscopy done. 
The only symptoms I have had is lower abdominal pain and pressure, on and off burning when urinating, increased heart rate and I can feel my heart beating in the middle of my stomach. 
My boobs have only been sore before my period and that goes away once my period starts. 
I think I'm just so worried that I am, that it is making me stress even more and take every little feeling in my body as a symptom!! 
I think I just need someone to set me straight and tell me I'm overthinking it!