Ok for 15 birds
Then make both the run and the coop a bit bigger, or reduce your numbers to about 10 to 12, instead of 15. Think in terms of 'how much room can you give your flock', rather than 'how many chickens can I cramp in the space'. Nobody has ever regretted giving their flock too much space. The coop will have just over 4 sq ft per bird. That isn't really enough space for them to spend several days at a time in without getting stressed. It will be fine for spring/summer time, but come winter, that coop will be crowded. You really don't want to have overcrowding stress.