It keeps pretty well in the deep freeze actually. But while that link said 6-12 mos the people we worked with (including NICU staff) said 6-8 mo. Some of mine made it 9 mos, but I don't think I'd "count" on it making it a year. Really just check it when it thaws to make sure it's good/not spoiled. But I wouldn't stress about it, if she likes getting it just from mama she's still getting all the benefits from it. And don't think of any milk you have to dump as wasted it still played a very important role in establishing or maintaining your supply even if she doesn't get around to drinking it.
It can also be use to make your own babyfoods or you can use it to cook her grains (or pasta) as a toddler--just make sure you cook slow at a low heat you don't want to overheat bm--or make her smoothies, etc. I think read something once about making soap with it but I never did it--the kids used it for food/drink too well! :LOL