You should be proud. I have to admit that I would have been incredibly "un-inspired" had I received what you did to make a T-shirt quilt. In fact I probably would have told the person I couldn't work with that. Kudos to you for following through and with stupendous results at that!
For me half the fun of T-shirt quilts is looking at all the different imprints and trying to put them together in a pleasing way.
Whenever I have been asked to make one I tell people how many shirts I need but I am only counting imprints. Looks like you got a lot of fabric out of those few shirts. The quilt looks great.