chances of being pregnant without sex???

my period was april 3-8th. i have been on birth control since march 10th. my boyfriend and i fooled around on april 10th. we were both naked and our parts touched for like 2 minutes by grinding on each other. i know what precum is and how there is a slight chance of pregnancy bc of that but his penis never went inside of me. i gave him head and a handjob after all that then he came on stomach. it was really hot in his car so i waited to put my jeans back on for a while. my period is supposed to start the 2nd or 3rd of May.....could i be pregnant from this??? last month i spotted brown blood a week before my period bc of my new birth control so if i do that this month should i freak out??? please help i’m only 16