Wow, I LOVE your coop!!! Really nice design! You should add the link in your personal details so you will have a "My Coop" under your avatar.https://www.backyardchickens.com/articles/eastern-shore-classic-coop.73500/
Check out the coop I built. It's roughly the same size you are looking for. It could be modified to fit you concrete pad. I'd be happy to answer any questions. Having a poured slab should make your built that much easier.