Nittanygirl, let me try and weigh in here:
First of all, I can totally relate to your rush experiences. Rush is confusing, it's hard, and like others have said, it doesn't represent "real" life or what truly goes on within a chapter.
For example, a chapter that isn't so great at rushing may have a wonderful, peppy sisterhood full of love and warmth that just doesn't show through during recruitment for one reason or another. It's such a shame that so many girls don't get to see the potential in certain chapters due to a lackluster rush.
BUT, also, it's totally OK to feel confused! During rush, there's a ton of pressure on PNMs to say and do the "right thing," all while meeting an onslaught of amazing and very different women AND being expected to pick a favorite in just a week. It's part of the process, and there's no reason to beat yourself up for making mistakes. It happens. Brush it off and keep going! You will make it.
I also felt like I wasn't "being myself" during my rush at times, and honestly, "be yourself" is such hard advice to swallow, because rush is so formal and intimidating, or at least was for me. How exactly do you "be yourself" when you can't say X Y Z, when you have to condense your entire story into two-three sentences...it's tough, but it's how we recruit, so don't stress too much about it, in my opinion.
Plus, I think it's amazing you got 12/13 houses! But I do want to stress (and echo) what others have said: your experiences during recruitment DO NOT necessarily reflect the chapters' experiences. My chapter had trouble with rushing when I joined, but your pledge class can make a world of difference in the sorority.
If it so happens that you only get called back to your "least favorite" houses, I urge you to remember that those women saw something special in YOU, and regardless of who else cut you (cutting girls is often really hard!), take pride in the fact that sorority women are interested in you joining their chapter. It's a really amazing thing to be a part of.
Best of luck, girl! Hope I can answer any questions/concerns, because I really do empathize with girls going through rush.