I killed Mr House when he asked me to kill the BoS.
There's your problem right there. That quest is called
The House Always Wins V, so that means you've completed THAW IV involving the Omertas. However, when you complete THAW III, involving the Boomers, you fail the NCR quest
Don't Tread on the Bear, and failing that quest removes Colonel Moore from the game forever -> see the referenced warning here:
Warning: Completing Part III will cause you to fail Don't Tread on the Bear which will lock you out of all NCR quests.
Source: http://fallout.wikia.com/wiki/The_House_Always_Wins#Part_Three
Failing this quest will cause Ambassador Crocker and Colonel Moore to disappear from the game world, to reinforce the idea the player is no longer able to continue down the NCR quest line.
Additional Reference Source: http://fallout.wikia.com/wiki/Don%27t_Tread_on_the_Bear!
Given your actions, it appears a Yes Man or Ceaser's Legion run is all that's left for you to do on this current character barring reloading an older save. That's assuming you haven't ticked off CL either, in which case Yes Man is all you have left. Hope this explains things for you.