Unprotected Sex. Had Light Pink Spotting. Sore Breasts, Exhausted, Crampy. Pregnant?

I recently have had an incident where me and my partner had unprotected sex. He did not ejaculate in me, or at all for that matter, but ever since, I have had strange symptoms. I had my period in March that ended on the 12th (the following week is when the unprotected event occured.) My period has always been irregular, but I do get it every month. Hopefully I get it this upcoming week, but about a week after the unprotected event - I spotted once. I went to the bathroom, went to wipe, looked at the paper, and there was a light pink blood, not a lot, just enough to notice. And that was that. This has never happened to me before. Is that a sign of implantation? Also I have had incredibly sore breasts, feel exhausted all the time, occasionally cramp, and am moody. I usually get moody and sore breasts before my period, but not like this. Am I pregnant? If the spotting did indicate implantation today would mark a rough guess of 3 weeks or so. Is it too early to use a home pregnancy test?