Brown discharge

Hello! So my SO and I have been TTC for a few months now, more actively trying recently. I was supposed to have my period but I didn't. I wiped and there was pinkish discharge and then it turned to brown. There was a time that it was red like period but then went back to brown discharge. I'm wondering if this could be implantation or not. I've taken pregnancy tests and they come out negative. I haven't had any period symptoms like I normally do, so I'm just really confused right now. Help please!!