The only way for a woman to get pregnant is for semen to be ejaculated into the vagina. Fingering someone when you potentially have traces of semen on your fingers is highly unlikely to lead to pregnancy, as sperm don't last long outside the body and, in addition, the amounts are probably too minuscule to lead to conception. In addition, if your partner was pregnant, she wouldn't show symptoms associated with pregnancy that quickly. It takes more than three days before the fertilized egg even implants on the uterine wall.

If you're going to be sexually active I strongly advise you use some contraception method(s) so as to cut down on the worry if something doesn't go as planned. You'll both feel a lot better and will be able to enjoy sex a lot more freely.