iMessage/FaceTime Problem on iOS6

iOS and iPadOS
ok here goes, i've been using my username/pass for the last 3-5 years, so i assume i know how to put my username/pass but on the other hand, on iOS6 and after upgrading, my devices just went out of sync. after lots of experiements turns out that my iPhone is picking up my phone number, and not my username/pass *normally it should be both* naturally, i try signing in through my user id..and its always notifying me that my username and/or pass are incorrect..which is not true, so now i receive the stuff on my Phone seperately and on my iPad/Mac seperately too *since those are effectively on my Apple ID* i need help/clarification on that regard, is it a bug? has it happend to anyone of you out there? Please Reply Regards,