Implantation bleeding?? HELP!

Sorry TMI yall! Alright so Im very confused about this! I had sex on December 8th, which was the last day of my ovulation (we are trying to get pregnant) took a pregnancy test yesterday because my period was late by a day, but was negative.. ): Then last night I started spotting light pink, so I thought it was my period and put a tampon in. This morning when I took it out it was brown and light pink. Still bleeding but very light and light cramping but nothing severe. Is this implantation bleeding? Need yalls advice!!