My last period was 3/2. My husband and I had sex and are ttc, on 3/13 and 3/15 abd 3/16. My cycle is 25 days. I am due to start my period 3/27. I started spotting yesterday a.m. with bright red discharge, and is now just brownish reddish black. It actually looks like my period does on my last day. Could this be implantation bleeding?