Doctors tell me if you even miss one dose of the bc pill you should use another form of contraception for the rest of the month. Even missing one pill can leave enough room for ovulation (releasing of an egg). It's not like it's a big deal... It's only the rest of the month (of the pill pack, I mean). Better to play it safe.
The morning after pill needs to be taken like.. 72 hours after possible conception. If it's been a week or whatever it's probably too late. It doesn't hurt but it's a huge dose of estrogen so i've heard it makes you really, really crabby for a while... Bleeding, cramping, etc. It's only something like 85% effective anyway. And the chances of you being pregnant from that one encounter, even if you did ovulate? Slim.
But don't worry. Just keep playing it safe, k? You can't take two pills on one day and expect everything to be in order again. The pill is a delicate thing. And like I say, if you miss one, just use condoms or spermicide or whatever until the end of the pack (that includes the placebo week). If you are pregnant, congrats! You'll be fine.