Could I have endometriosis if bad cramps?

Yes. One of the main symptoms of endometriosis is painful periods. While there is not really a correlation between the amount of emdometriosis and the amount of pain, endometriosis clearly causes pain and should be considered in anyone with painful periods.
Agree. We are working on a paper that reports in teenagers who had bad periods (either keeping them from school or worse than peers), 100% have had endometriosis at laparoscopy. In the older age groups such as 20's or 30's, most women don't have much pain and in fact, most present with infertility. Painful cycles in the older age group is usually due to adenomyosis, endo in the muscle of the uterus.