Janie,
I apologise if I have misunderstood your situation.
My instinct is to suggest that you sing the songs you know, whether you repeat them or not, and if you are unable to learn more over a time - sure - use a prompt sheet if you have to. But having said that, I still am not convinced that anybody can interpret and enjoy the songs while they are being read from a page, either singer or audience.
But I think the argument here is wider than the situatuion you pose. We are talking about the general use of crib-sheets by people who are able to learn songs, but don't or won't, for one reason or another.
Blogward describes a strange situation of reading from a large sheet of paper so he can can 'keep eye contact with the audience' - sorry, that one lost me altogether.
Can I re-iterate what somebody wrote earlier; the question of singing from a book is a relatively new one; I honestly haven't witnesses it to any great degree in any of the clubs I have been involved in to any great degree, and I believe that the general standard of singing was far higher than it appears to be today, as was the understanding of 'folk' song.
Jim Carroll