Is it implantation bleeding?

Okay, before I explain what happened during my so i hope “period”, I think you guys should know I have an eating disorder, which makes my period already really short and kind of lighter than usual.

Alrighty, so I lost my virginity the beginning of this month (Feb 2nd to be exact lmaoo) and we didn’t use a condom. He pulled out really early, he wasn’t even close to finishing. We also did it again a few days later with a condom, but then he took it off and we went for another few minutes, but he still pulled out before he was even close to finishing.

So I was anticipating my period to come and this entire month I tried eating well so that it would come and hopefully be normal, but the first day of my period, I got it at midnight and I had medium cramping, and a medium/heavy flow. The flow was constant the first 2 days but what I noticed when I first got it is my blood was brown. I was only 1 day late on my period and I read that if it’s brown it means old blood so maybe it just took longer to exit? Throughout the first day of my “period” I had pretty bad cramps and was in a realllly bad mood.

The second day my flow was more medium and I had no cramps, and then the third day my flow was really light. The last day of my period (my “period” only lasted four days) it was like nothing was exiting my body, so I just inserted a tampon and there was still old brown blood up in there.

I read online also that brown blood could mean implantation bleeding, but i’m scared to take a pregnancy test because i’m only 18 years old and i’m sooo not ready to go through this.

I’m also not experiencing any pregnancy symptoms besides mood swings (that may just be because i’m stressing a LOT because of this...) and i’m bloating/constipated (which i’ve experienced even before I had sex because of my eating disorder).