I say just got for it, Salix. It's like in your fic 'Suffering for his art' where Viggo's image of Orli just wouldn't go away until he'd photographed it. Something is telling you to get out there and paint so do it. Even if they do suck you'll have satisfied that need inside.
I make my own beadwork jewellery and sometimes when I get an idea for a piece, it just won't leave me alone until I do it and get it out of my system. I feel so much happier when it's done. Same with my fics.
Go do it...and best of luck! :)