Enna, I'm so sorry
Rush is so arbitrary sometimes; I know there are ADPi's who wanted you at pref who are at least as disappointed as you are. Rushees and sisters both suffer disappointments during rush.
You are absolutely right, you don't need to be a greek to feel worthwhile. It sounds like you're making the most of your college career with all of your activities and, what's more, you sound like a great girl who got caught in a numbers game.
If you decide to give COB a whirl, please let us know how it went!