You shouldn't feel like a failure- on the contrary, you should feel like the world's best mama!!! And even though your LO seems done, you never know- she may want to nurse again. (My kid has been weaned for over a month and last night she wanted to nurse- I'm the one who said "no.")
Give yourself a big pat on the back for a job phenomenally well-done, and go out and buy yourself a really nice bra. You've earned it!