Implantation bleeding?

So last Saturday (July the 15th) I had sex with my bf ( we used condoms but I'm not on any birth control) it was two days after my period had ended. Then, yesterday (the 22nd) I felt like a lot of discharge come out so I went to pee and when I looked in my underwear there was some brownish blood. I think I had some brownish blood when I had first woken up also but I was so tired I wasn't sure. Could this be a sign of me being pregnant? I can't get a pregnancy test yet so I will have to wait until the 9th to see if I missed my period. Are there any other things that could cause this? I hope it could be left over period blood but there was more than I thought it would be if it was just leftover blood. I haven't had anymore blood come out yet I believe but Im staying attentive lmao.

Also should there be other signs I should look for if it is pregnancy?