implantation??

Morning everyone! So I'm 8-9 dpo AF is suppose to be here according to glow the 18th-19th. I've been extreamly tired lately and my nipples have been sore not to mention feeling emotional for no reason. I wanted to take a pregnancy test but already know it's too early. Well this morning I wiped and there was light brown on the tissue. I mean light enough that it looked like someone just dropped brown water on it. Could this be implantation bleeding? I didn't have this with my first pregnancy so I'm not sure what to expect.