Any suggestions?

I went off the pill after 8 years about 3 months ago,  since then period has remained on pretty darn close to the same schedule as being on the pill. DH and I just started trying this past cycle AF 9/3-9/9 and predicted ovulation in 9/17. Had intercourse on 9/11 and 9/17. AF predicted due back 10/1, however started bleeding last night very light and this morning very heavy. My question is, has anyone experienced implantation bleeding, and if so does it resemble you period? Or should I just chalk this up to my period being irregular due to going off of the pill?