Possibly pregnant ? SOS

Need help, I’m stressing out because I went to visit my bf, at the time( i ended up finding out he was talking to other girls when I was with him), around New Years and we had shower sex while I was on my period and now my period is late by almost a month and I’m having weird off and on spotting and today while I was in class I got really bad cramps and I went to pee and realized I was bleeding, at this point I thought I finally started my period but 3 minutes later it stopped completely. Idk what to do I’m currently trying to finish undergrad so I can move onto vet school and I just can’t have a baby right now & im too scared to buy pregnancy test to check because If I am I won’t know what to do. 😭

My period is usually irregular but not this bad

UPDATE: I took a test and it says no with no faint lines or anything but wasn’t morning pee. Should I take again in morning or should I be good ?

If my next question is what’s really going on with me then if I’m not pregnant 🤦🏾‍♀️