I have primary dysmenorrhea. Last month I came on 2 weeks after my periods but had no cramps which has never happened. Could I b pregnant?

I don't believe that. I understand what you are trying to describe. If you had a period then you are not pregnant from sexual activity that occurred prior to the period. If you aren't sure if you had a period then go ahead and take a home pregnancy test. Lack of cramping does not equate to pregnancy however.