Chances of pregnancy?

My boyfriend and I had unprotected sex. He had precum on his tip but we wiped it off on my shirt then waited a minute then he went in partially for a few seconds then he pulled out and we squeezed the tip for the precum and wiped it off. We did this four or five times. Three days later we had protected sex with just precum and three days later (today) we had protected sex again with just precum. My period is due around 3 or 4 days from now and im usually only late or early by a day or two each month. What are the chances of pregnancy?