Funny how that is with artists... it's just never good enough. My older sister was also an artist. She had her degree in painting. She did absolutely beautiful work, but in her mind, it all sucked.
I treasure each piece I have from her.
She once sent me a drawing of an empty box of chocolates, complete with all the crumpled empty cups that the chocolate had been in. It seemed she couldn't resist eating it, so I got the empties.