Help!!!

Haleigh
I'm kind of in a tight bind here.
​I don't feel right, I'm nauseous, and dizzy. 
​I had sex on one of my fertile days only using the withdrawal method, my " period" came 4 days early. It consisted of a day and a half of bleeding plus 2 days of brown spotting (only a tablespoon's worth for the past 2 days though.) I'm really worried I might be pregnant. Is there a chance?