I think we have two more episodes before the Red Wedding. Episode 7 next week is the Bear and the Maiden Fair, so it should include Jaime rescuing Brienne from the bear. Maybe Sam the Slayer as well since they set that up this week by having Sam show Gilly the black dagger. Episode 8 is called Second Sons. I assume Tyrion and Sansa will marry in that episode. Probably Jorah will get busted for his prior spying on Dany.
Episode 9 is the Rains of Castamere. That pretty much has to be the Red Wedding given that the biggest events always happen in Episode 9 (Ned's beheading in season 1, battle of blackwater last season). Plus that is of course the song the band plays when Catelyn realizes what's about to happen and the shit all goes down.
Episode 10 is Mhysa which I assume means Dany takes Yunkai and all the slaves call her Mhysa ("Mother"). Probably the season ends with Beric giving his life force to Catelyn as well which would also be appropriate for the Mhysa title.