Hwils I don't have endo nor know anyone with it so I can't help with that, but there is, I think, a support group for it/discussion group here somewhere.

As for not having your period, as LittleO said do you know when you may have ovulated? Or if you did? If it was later then your period (if you didn't conceive) would be later as the time from ovulation to the first day of your period (luteal phase- sorry for explaining, not sure what you do-don't know about cycles) is roughly the same length month to month.