Missed period!?

Hi guys im 19years old already got two little boys with previous partners but ive been withy new partner nearly 2 years now and I havent got pregnant but have still missed period due to stress or something like that? Today is my period date for what I have worked out but also normally its the 19th of each month could this mean I have actually conceived a little prince/princess or could it again be down to stress even though I haven't been feeling down?