Almost 2 full cycles late, was nursing.

I was nursing on demand until Feb 8. after that day I went to irregular pumping, to not pumping at all. I tested around my expected period time, negative. now I'm 20 days late and getting worried that I may have ovulated at some odd point. Not having a period is freaking me out. I haven't nursed in at least 3 weeks and nothing feels right, right now. I'm cramping, bloated, nauseated. I can barely eat. I'm hoping it's just stress and hormones fluctuating. my question is... can abruptly stopping nursing cause your cycle to shift? to this extent? I had 2 regular cycles before all this happened. I'm 5mpp.