confused!!

I had what I thought was my period on July 1st. It was just a little spotting as usual in the beginning. Well it last for a day maybe 2 days, and i thought nothing of it. Usually my periods are 4 days but I figured it was short. Come to find out my actual last period was may 22! It is confirmed I am pregnant. What would you consider the spotting on July 1-2? Is it Implantation bleeding? If it is then when would I have conceived? I don't have sex often with my boyfriend and when I do I don't track it.. lol. Just curious when I conceived/possible days for sex? Given that I had implantation bleeding on July 1