Am I pregnant!!

3 weeks ago my boyfriend fingered me he he was touching his penis before he fingered me and went straight into fingering me after and didn’t wipe his hands I couldn’t feel anything on his hands but idk ? I am 5 days late on my period today I had brown coloured diss charge I haven’t been really been experiencing At pregnancy symptoms however today I’ve had bad back pain and cramps is this because of my period may be coming ? I’m freaking out what’s the chance I am pregnant x