Your post really resonates with me. My boyfriend is moving in right now and I had to create room for his clothes. Part of that was donating clothes that I don't need. Giving away my children's sized pants that I wore in college really upset me. I was noticeably down for at least 2 days. I've been pretty much the same range (+/- 10lbs) aside from the 1 fit year in college, my pregnancy, and when I put on weight working with a nutritionist. When I listen to my body and just eat what I do, my weight doesn't really change.
I have a very hard time accepting that this is what I'm supposed to weigh. I am a curvier woman, but I don't want to be curvy in the thighs or arms!
When I gave away those clothes, I felt like I was saying "I give up, this is where I'm going to be forever." That thought is so depressing.