Wow, this is definitely one of your better ones.

"mistakes explode through every pore of my body" and "composed of rainbow-coloured-atrocities" = sheer brilliance.

Diction is steadily improving, I'd say, and your metaphors are getting better. Paints a beautiful, but saddening picture, this one does.

The first line of the second stanza has me confused, though...a bit nebulous.

And by the way, you're not worthless, and you're definitely not nothing. You can write poetry worth a damn, that's for sure.

great poem, i really liked it!