I am between two and three weeks late,one pregnancy test is

Hi,I'm 20,married,not on birth control.
I'm not exactly sure when my last period was,as is I work a lot
And don't have time to do the right thing,and keep track of it on a calendar.
The last period I "remember" is November.
I might have had one in December,but I just don't remember it.
I haven't had one in January at all, no cramps,no bleeding of any kind.
I feel as if I have gained a little weight though,maybe 2-4 pounds,not sure how much,but I do notice I feel heavier.
I'm a thin girl,I don't gain weight very often. I was wondering if that could delay a period,or cause it not to come
Also if you know of any uncommon pregnancy symptoms,please list
some.

thanks.

LOTS of stuff can cause it not to come. Stress is one of them, medications, ect.

I would take a pregnancy test. If you want to know for sure see a doctor and request a blood test not a urinalysis