I'm not positive, but I thought blockchain.info had a setting you can use so that a new copy of your wallet is sent to you every time you add a new address. If/when the site comes back up, you might want to look into that setting.
It does, actually, and I had it on, which is why I'm perplexed about the fact that my last backup in my email account is too old. I was so sure it would send the backup automatically, that I didn't bother to check I actually got it
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