Did Not Have Sex, Got Fingering Done. Later Found Irregular Brown Discharge. Worried If I'm Pregnant Or Anything Else?

Hello,
Me and my girlfriend are extremely scared right now. We started fooling around for the first time a month ago. However, I have only fingered her twice. The first time being about 3 weeks ago and then the second about 2 weeks ago. Both times I fingered her she gave me a hj and made me cum but she did that after I had finished fingering her. After doing it for the second time she felt extremely guilty and it really upset her and we haven't done it since. Those are the only two times that we have both had our underwear off or genitals touched at the same time. She became really scared though because after I fingered her for the first time I was too rough and she said it hurt, and later that day she later told me she found a brown discharge in her panties. It eventually stopped and do she thought nothing of it. However after doing it the second time she found the same discharge in her underwear. This really scared her but eventually it stopped again. And about 5 days ago we started fooling around again but only for a few minutes so we didnt go very far, to the point that all clothes were still on. Later that night she found the discharge again which really scared her. She had here last period starting around April 1 and so she was expecting her period around the 29. She became extremely stressed and worried over the fact that she has still not received her period although she never has kept track of her period so she does not know how regular she is. Two days ago she thought she recieved her period but it was simply discharge although this time it was a white milky color which she said was comforting because she said that was normal for her. Lastly, since about Monday she has been feeling period like symptoms, specifically on and off cramping and back pains (although she has back problems so this is not unusual for her at all) but no blood. We are worried over the possibly that she is pregnant. However we never had sex nor did I ever sum near or on her vaginal area. It seems to me that it is highly unlikely that she is pregnant because of this as well as the fact that she does not display any other pregnancy signs such as nausea, sensitive breasts, heightened sense of smell, fatigue, head aches, food cravings. Am I wrong to think that she isn't pregnant? Please, your help would be greatly appreciated she is only 17 years old and we made a mistake. If she isnt pregnant, what can explain the lack of period but pms symptoms?