We of course can't tell you that, but I don't know if your grades were the problem. You can check with the Greek Life office to learn what the grade requirements are. I think most chapters do grade cuts after round one.
"Lots" of organizations concerns me. Don't spread yourself too thin and make sure you're getting involved in things you really care about.
I can tell you that LAST year all but three or four soroities did spring rush. I imagine that who does recruitment depends greatly on the size of the fall pledge classes. In the fall I know (but do not know about spring) if you maximize all your options you will get a bid.
UCLA, by virtue of being fed many students by CCs, have less stigma to upper classmen. BUT, to be repeated ad nausem, I can't tell you that you will get a bid from the house that you want.
And give that chapter you wouldn't give a chance to on Pref night another chance, if they'll let you. In an informal environment you'll probably find them much more desirable.