what are the odds that I am pregnant ?

Me & my boyfriend have been using he withdrawal method, error free for two years. But last night he accidentally came inside of me. I was wondering what the odds are that I could be pregnant because I know pregnancy isn't a guaranteed thing. My period should come in 9 days & my fertile window ended 3-4 days ago. Thank you ! 
PS: can't take plan B because i weigh too much for it to be effective ( it has to do with the enzymes the liver produces ) and also don't think I can get a copper IUD put in within 5 days ( i work full time , and I reaaaaally don't want one.