Hey mmom,
Yes, general rule of thumb is that it takes up to 2 weeks for the milk protein to get out of your system, (then up to another 2 weeks to get out of your LO's system).
Big big (((hugs))) it is SO disheartening to get rid of that stored BM. I had to dump loads of it (couldn't donate because I was on meds as well that donation centers wouldn't accept) and it stunk!
As deb mentioned donating to hospitals/centers is a great idea. I couldn't donate mine because of a med I was on at the time, but perhaps it would be an option for you?