could i be pregnant need advice

it is my fertility window at the moment my boyfriend and i had sex 3 nights ago and the condom came off inside me it was far in and i couldnt find it to take it out that night but felt again the next day and found the condom and took it out but it was empty could i be pregnant? i had my son 3 months ago when should i do a pregnancy test or go to doctors? my last peirod was a week late but due on my period on 3rd of october