Aww, thanks for all your support, ladies. I'm not as depressed about this as I sounded last night -- I know that getting five invites (and two of my three favorites) is definitely not a bad thing! I heard some horror stories from girls who only got asked back to three houses, so I'm feeling comparatively lucky to have five.
I don't know for sure that the reason I got cut was because I was a sophomore, but I know that recruitment numbers are up quite a bit this year and the sororities were probably flooded with really awesome choices of PNMs, in which case it totally makes sense to choose a freshman over a sophomore. I'm sure there could be other reasons why I was dropped too, but I'll never know what they were, and blaming it on being a sophomore is a lot less painful than worrying about why people don't like me or whether or not I'm pretty/cool/fun enough.
I'm going to stick with rush at least until House #2 drops me. If that happens, I'll re-evaluate my options then, and if they don't cut me, then . . .

I did really love House #5 during first rounds too, but I can't really tell yet how comfortable I'd feel there -- I guess that's what tonight is for! And as for House #4, I didn't get a very good feel for them the first time around so I'm glad to be going back.
Thanks for helping me keep things in perspective -- I know things could be worse.