Implantation or period???

I was due for my period Sept 13 but it didnt come. The 15th thru the 18th I spotted which was light pink when wiping but the 19th I bled a little while peeing (nothing on my pad) then I bled a little heavier had little clots/flakes in the toilet.the 20th I bled but today (for now) its gone.its Not to heavy just bright red but it came with cramps on mostly one side and bad lower back pain. I'm having afew symptoms but it's hard to tell if it's a period or pregnancy??? Also I pinched my nipple  and I'm still able to get "milk" to come out my littlest daughter is 2 I havent breastfed since she was 10 months??? What's that about? PLEAASSEE HELP.