Late period

I'm late on my period about 3 days and have normal PMS symptoms. I'm not super worried about anything but was wondering if being super sick during my last period and/or starting to exercise a lot after a month and a half of not could've messed up my hormones or something causing my period to be late. 
My boy friend and I do play around(but not intercourse) a bit but we're both always careful (like if he's close or not) so I'm not super worried about being pregnant or anything especially since I have my normal PMS symptoms. 
I'm more wondering if being super sick at the same exact time as my period (pretty much starting and ending on the same days) and/or starting to exercise a lot the day after being sick could've just messed things around or something causing my period to be late.