Hiya,
(not a doc just a fellow pill user!)
If you weren't on the pill i'd suggest the morning after pill. But you are on the pill and as long as you have taken them correctly every day, not missed any, vomited, food poisoning etc then you are more than likely backed up.
Although when you say 12am at weekends thats as in midnight and not 12 in the afternoon right? Otherwise you'd be leaving a window of 10-11 hours. But i think you meant midnight.
You say you've never missed a pill so i'd relax. The pill is extremely effective and you've done nothing to reduce that effectiveness. Remember even if you hadnt been using a condom you would have been just as effective so dont worry about it busting. That was just there as a second barrier or barrier to stds.
Hope that helps!