Older Amy don't count. She was an alternate Amy with 36 years that the other Amy did not have (in the same fashion, 5:02 Secret Agent Pond is also not real Amy, but Series 5 and Series 6 Amy are the same person). Plus, she didn't sacrifice anything as all she did was make sure she didn't exist. She should not have existed and she chose not to. Any other outcome would make her horribly selfish, which she was. At least Karen was a good actress in that one. But it's an idiot plot that could be resolved in minutes.
On the other hand
Curlers
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Amy's Choice, killing herself to be with Rory. Maybe that was self-less, making this her 2nd selfless act. Not sure because it was suicide and all
Inconsistent scene: at the end of 11th hour (Season 5, Episode 1). We see Young Amy on her suitcase waiting. It is the morning and she has waited all night. Then we hear the TARDIS sound and she looks up with excitement. We immediately cut to Gillan's Amy being woken at night by the same sound. The scene is never explained (and Doctor Who rarely has dream sequences). Now it has. Although, this would change a lot of things, as Amy was always a bit cross about having to wait her decade for the Doctor, and apparently, she would not have had to as the Doctor explained to her. So basically, the Doctor still traumatised a kid. On purpose this time.
Also, this episode condoned double suicide. Discuss.