I Have Irregular Periods Since I Stopped Taking My Birth

I have irregular periods since I stopped taking my birth control the longest time between periods being 49 days up until this month. I haven't had a period in 63 days and still waiting, the smell and thought of chocolate has been upsetting my stomach the past week and my chest seems bigger and I've been really grouchy. I breastfeed my youngest daughter that is 1. I have taken pregnancy test for 3 weeks 1-2 times a week now and they've all come back negative. Me and my husband have been trying for another kid since November. I also have PCOS.

My question is what could be causing my period to be so late?