How abnormal is too late for a period if i miss this month & go till next month & then i get it? im experiencing stomach pain on and off at times too

Tricky to say.: Ok, first, with birth control pills or polycystic ovary syndrome (at least 5% of women have this) then, this often happens. There are a lot of causes for this you don't have (clotting bleeding problems, pregnancy) but it is worth setting up the regular GYN visit you should have anyway. Here is an overview, http://www.nerdpocalypse.net/diseases/female.html