Oh my goodness, do not feel guilty one little bit! I've looked through quilt books and have seen quilts that I like and used their ideas and made my own quilt and didn't buy the book because I only liked one quilt. I only buy books if I want to make quite a few of the quilts. If you can figure out how to make the quilt by just looking at the pictures, what is wrong with that? You said there was no pattern, so why would you buy the book in the first place?
I am Catholic and have Catholic guilt up the ying yang all the time, but I don't get it by looking at a pattern and figuring out how to make it on my own.
Especially when you are in University, how can you afford to buy more books? You aren't cheating. You didn't take a copy of the directions. You just looked at the pictures and figured how to make it. So, please, if you have to feel guilty about something, make it something worthy of feeling guilty about. So many people just look at quilts and figure out how to make the pattern. You are doing the same thing.