Implantation bleeding

Has anyone ever had implantation bleeding? My period wasn't due until Monday but starting on Thursday around 10am I started spotting and still every few hours I'll spot a little bit and it's dark red/ brown but it's the third day and I read that if it's longer than 2 days it's not implantation bleeding but when I get my period it's always like super heavy 3-4 tampons a day... Help!! And my BF and I are TTc