What are the chances of getting pregnant ?

ok, so i have been on yasmin bc pills for 6 months now and never missed or been late on a pill but i was wondering what the chances of getting pregnant when you have on the 5th or sixth placebo pill. i mean my doc says that in cover even when im on my period pills but just in case what do you say? i know that there is always a chance but i need your opinion and stories..... preferebly pill users but any answers are fiine thanks