morning after pill - pregnancy chances ?

Last week me & my partner had problem during intercourse - the condom slipped off!
Since this was a weekend and everywhere was closed, when i eventually got the morning after pill it was 16 hours later.
I had what was like a light period about 3 or 4 days later, of which i have just finished.
I am now on the pill and to be sure will continue to use normal contraception, but i was wondering if there was still any chance of me being pregnant as my period isnt due for about another week?

Many Thanks .