Cece,
I totally, totally understand your feelings - I could have written your post myself 12 months ago.
It was such a bittersweet thing to know I had reached my goal of 12 months but had to give it up. I know for me it was true what Lisa said, that feeling of needing to pump to keep up supply had become so ingrained - it took me ages each time I even reduced the number of pumps I was doing. And stopping altogether was too hard to get my head around.
Like you I had enough to have fed her for 12 months on frozen EBM but it became really important to me to pump for that long. It was a silly little thing maybe but it felt like it was all I had left. I had made such a huge emotional investment in that damn pump! as long as I was expressing, I was feeding my baby, and maybe even a small part of me that felt as long as I was expressing, she could have been BFing (even though she never did).
I can't explain it more than that, just that there definitely was a big emotional attachment to expressing, and it was hard. That's why the 12 month mark was a good one, it was a very solid point at which to say ' will stop here'. And my DH was happy to let me do what I needed but he also needed to know there was an end in sight.