I had spotted about 2-3 weeks ago and for 2 weeks now I have had cramps , moodswings , breast tenderness , enlargement of nipples. My period is not due for another 3 days. Is there a good chance I'm pregnant?

If you've had sex, there is a good chance you are pregnant. However, with that said, you are going to have to wait to see if your period comes. If not, test using first morning urine.

I also want to say that what you are experiencing are very common premenstrual symptoms as well.