late period, on the pill

so i've been on the pill for 3 months now, i take my pills at the exact same time every day and i have the 21 day packs. after taking the second pack i forgot i was supposed to stop taking pills for a week, and i went straight to the third pack.
my doctor told me not to worry and just finish the pack i started, so i  just finished the third pack. (keep in mind i've been taking my pills exactly on time). i'm in that window to get my period this week but i'm 6 days late and i'm a little worried considering the fact that my boyfriend and i have been having unprotected sex for a few weeks. what should i do?