Rule of thumb is 3-4 sq ft per adult bird inside the coop and a minimum of 10 sq ft of run space per adult bird. So, yes, based on what you're adding, you'll need a bigger coop. 6 adult birds x 4 sq ft = 24sq ft. I like to give my birds as much room as possible so they don't get crowded and start picking at each other. Just make sure you can reach the back of the coop for cleaning. I'm currently running into that issue. To add on, I'd take off the human door and storage door and build that section out another couple feet and place the doors back on the new section. Hope that helps.
I really like your current set up. It's very nicely built and the clean out tray is awesome. 
