I agree with Blackharted, sometimes I also get bored to mention long lists of credits :) (and usually I have to edit the image once or more times 'cause I always forget to mention something :P) and anyway you're not obliged at all.
I certainly prefer that a picture is commented by the author for what it means to him or where he/she got inspiration or that is posted with a nice story that goes together with the pic rather than any list of credits.

Don't worry about it! Hope this will make you feel better and that you'll continue sharing your art with us :)

~*Siliphiel

www.aerysoul.com