why is my period late?

My period is a couple of days late and I was wondering why.. 
-I take my birth control every single day within a 3 hour window if not the same time 98% of the time (the other 2% I am a couple hours late) 
-I have sex but along with the birth control I use a condom every single time and sometimes even have him pull out (I'm a little nervous)
-I am very stressed (partially just because I'm an anxious person and partially because of my period) 
-I work out or do recreational walking/running probably 2-3 hours a day 
-the past weeks my caloric intake has been low due to lack of hunger (1000-1400) 
-I recently went on two vacations within two weeks where my workout/low eating routine was interrupted. 
These are all of the main factors I can think of. 
Any ideas??