What to do about choral singing and private auditions?

At my high school, I was in the modern choir for a semester. my school has a record of something like fifteen years of superior ratings at our state choral festival, and this year, we maintained that all-superior ratings status. It's one of the best female choirs in the state, and the school has been known to do choir tours. in June, we took a choir tour through Canada, singing challenging pieces, including Litanies a la Vierge Noire by Poulenc, which is the most difficult piece ever attempted at our school, according to the choral director.
My problem is that, while this looks really good on paper, I personally am a poor singer. I may blend in a choir and therefore do well, but on my own, I'm not a soloist and couldn't "belt it out" Broadway-style if I tried. on my own, I feel like I may hardly carry a tune, but when I'm singing with other people, or once I've rehearsed a piece a lot, that changes.

** in college, I would like to proceed singing, either in a choir or in a female acapella group - I think the latter would be especially awesome. I know that humans have to audition privately to be admitted to these programs, and I don't think that I could do very well in one, with the anxiety/tension of an audition added to my already weak solo voice. I really do take delight in singing, though, so does any individual have any counsel or suggestions? would big schools like the University of Notre Dame have alternatives? Do you think I would have any prospect at all?

Thanks!