3 weeks late and nothing.

Ok so I had AF on nov 6th. I was on birth control, the orthro evra patch but stopped a week before I got AF on the 6th. I had a normal period but now I'm 3 weeks late and still nothing.  I have had early pregnancy symptoms but only on and off. So could I be just out of wack with AF or is there still a chance I could be pregnant? I'm not stressing about it or anything anymore just waiting around. I've read about orthro evra and they sai that you could convive as soon as you stop with it but I don't know.