no PMS symptoms?

okay guys, I have looked so many things up on this, but can't find ANYTHING. is it normal to not have any PMS symptoms. im 16 and I've never felt moody, angry, had mood swings at all actually on it or before;i have only ever had cramps once but i am not even sure they were cramps due to a uti following the day after. I have had my period for 2 years now and never experience any of the things my friends have(other than exhaustion). i also dont know if a 4 week period and a 3 month absence have anything to do with it(im VERY irregular). help?