Yes I'm On The Nora B Pill. Had My Daughter

Yes I'm on the nora b pill. Had my daughter in January and was breastfeeding her. At my 6 weeks I was just starting my period so I began the pill. Well I'd bleed heavy the after I'd end I'd start again in 4 days. My last cycle was April 25 2016. I'm now 10 days late and i don't know why. At 5 days late I took 2 PG test and they were both negative. What do I do?