Doubt about Angel Beats (spoilers)

[kakalxlax]

(this post contains spoilers, if you havent seen this anime i recommend you to stop reading and go watch it)

Hi, yesterday i saw angel Beats episode 13 and it left me with a doubt:

According to Kanade, she is in that world because she didnt have the chance to thank Otonashi for giving her his heart. Now, if Kanade was given Otonashis heart, the logic thing would be that Kanade died after him. But when Otonashi arrives to that crazy world, Kanade was already there for a while (a long time having in mind that they built that giant guild to build weapons to fight Kanade)

I was getting all emotional and then she says than and it left me thinking.

Its also said that Otonashi ended up there for loosing his memory, so we discard that he was put there to "save" Kanade, because it would have to be a great delay between both events and they are reborn after dying.

Maybe (and i hope so) i lost something that explains it.

(i still have to see 13.5 and 14, but as i heard they are only epilogues, and before finishing it i would like to clear that doubt so i can enjoy it as its supposed to )