4days late am I pregnant?

I'm always 28 days cycle with my period without fail. My last period was now 32 days ago. I took Yasmin pill at the start of my period for only a week then changed my mind and have been everyday with my bf unprotected. 8 days ago I had blood when I went to the toilet I'm now thinking this was implantation bleeding as it was so light. I been toilet so much the last week and bad hurt burn but other than that no other symptoms. I did a cheap test yesterday and it was negative. So I'm confused now