Implantation bleeding?

So I was sexually activate with a guy from June, to early this month & we only used a condom twice, which is sooo dumb I already know. I had a regular period in June, after I got off my period we were back on it without a condom once again. Then I was expecting my period & it never came until way after the date it was supposed to come but only got an extremely light pink discharge which I’ve never had before, it was not at all like my usual period which is normally a murder scene lol. So I went & got a test (first response) it came out negative, so I stopped stressing it & moved on. I had been planning on getting nexplanon but my drs office took forever to get me in & I just got in there the 6th & they literally put the implant in & did not test me for pregnancy beforehand, so now I’m experiencing extremely light brown discharge & I never really had a normal period before getting it put in. What do y’all think? Am I possibly pregnant & will nexplanon hurt the baby?