No protection

So me and my boyfriend did it for the first time like a month ago and with out protection and he only put it in a little and then we decided not to do it, I got really scared that there might have been a chance j could be pregnant, so I took plan b even tho ik the chances are slim. I told my mom and she FLIPPED so she took me to the dr and we took a pregnancy test (keep in mind this is all happening in a 3 day time period) and it came out negitave, she told me to wait till I got my period and then test again. Got my period, and now I'm late this month... What are the chances? Kinda worried, I haven't tested since