help!!!

Justine
So this morning me and my SO had sex and I guess the condom was a bit loose after he came the first time and I saw a bit of white ... SOMETHING ( maybe his cum or my discharge?? Idk ) 
And I noticed it from the noise from the condom as he thrusted it into me so I guess it may have touched the outer part of my vagina. 
I'm not on any birth control but should I take plan b?