I have several questions concerning the possibilities of getting pregnant..

Is it possible to get a girl pregnant by having the tip of the penis touch the outside of the vagina? Whether there may be a little bit of cum on the tip or not..

Is it possible to get a girl pregnant by accidentally touching sperm that was exposed to air and then fingering her?

These questions are for personal uses as my girlfriend usually has her period on the 13-15th of the month.. But it did not happen at all.. So on the 20th, we got together and i fingered her.. I remember touching my penis a little then getting back to fingering her.. And i do not remember whether i accidentally may have rubbed my penis up against her vagina or not.. But it's been 5 days now.. And her period has still not come.. We're both really scared that she is pregnant..