I touched my gf vaginal opening with precum on my fingers on 6th day of cycle ( her period cycle is 28-29 days . we are really worried that she might get pregnant?

Very unlikely, but: A fertile couple having sexual activities should be ready for whatever cute little surprise baby life brings (be married, settled down, with insurance). Sperm can swim but they need a continuous wet path to swim along. Thus, it depends on the details of each event. Sperm that make it into the uterus or farther, may live in a woman several days and be able to start a baby.