Do I need to add on?

Howdy All,
I'm an undercover chicken owner (by country rules, I'm ok; deed restrictions ok with horses but not chickens ). I currently have 3 fat and happy 2 yr old hens. RSL, BO and BSL. DD will be adding 4 more: 2 EE, 1 Delaware, 1 BR. We'll be getting them as day old chicks next week, and will keep them in the garage until 6 wks old or fully feathered.

I'm in Texas and have a warm weather style coop. In summer, it is a 3 sider; in winter, I add a sliding front which remains open just enough to allow them in/out. The coop is 3 feet wide, 4 feet tall inside, and 6 feet long, contains 2 nest boxes, and a 6 foot long roost bar. My run is 10X10 (x4ft tall), fully enclosed, predator proof wire top covered by a tarp for weather/sun protection. My hens are almost NEVER in the coop, except to lay eggs and roost. The only time they've stayed inside in daytime was during a major hail storm with 50mph winds. My run, therefore will be over sized, even for the 7 chickens, but my coop is obviously too small.

My question is: Should I add on, or will I be ok since they are hardly ever inside? Note: I cannot freerange due to high prey drive dogs and neighborhood rules, so the birds are in the coop/run at all times. Any thoughts?