You can keep 5 large fowl in there using the 4 sq. ft. rule. That's close enough. The current run will handle 7 large breed chickens fine. Now if your birds aren't going to be cooped due to cold in the winter, you are just fine and can coop 7 large fowl in your coop as long as they have access to the run. Shut them in at night to prevent predators
. If they need to need cooped for days due to weather, then you need to add additional room to the coop only for 7 chickens to live in there. 7x4=32, so you need 32 sq. ft. in the coop. 30 sf. will do if that is easier math for the build.
Best,
Karen. 2 nest boxes is fine for 7 birds.
------- One thing you can do if enlargng the coop is consider an "L" shaped coop. There is a nice one shown in the "Medium" coops section of the "Coops" gallery on BYC. That will eliminate you having to tear out any walls on the coop you have now.
Use 2 quan. 3x6 coops placed in an "L" pattern, both facing the run.