I really doubt you are pregnant but if he did indeed get sperm on his fingers after he ejaculated and then inserted them in you I think there could be a chance. But if he cleans himself off after he does then you are probably ok. As for sore nipples, they could be irritated somehow. If you are really worried you can always go into the doctor to confirm you are not pregnant. Hope that helps some.
Sounds more like you are PMS'ing. Although I guess it COULD be possible if there was sperm on his fingers, etc etc.....I HIGHLY doubt it. People try for months and years to get pregnant and aren't able to so I would say that the chance is highly unlikely.
Once that sperm hits the air it dies almost instantly. You didn't have sex, you aren't pregnant. Sounds like normal PMS symptoms, stress plays a HUGE factor in your menstrual cycles so calm down and it will come.
I don't think that there is even a remote chance that you are pregnant, the chances of getting pregnant on those conditions are nil.
Anyway your sore nipples may be due to heavy foreplay or rubbing, sucking, etc.
Don't stress you are not pregnant, PMS can somtimes cause painful nipples or as Mumita said heavy foreplay.