Most damsels are known to be territorial and quite aggressive although some like yellow tail damsel and other demoiselle type damsels are not too bad. Your damsels (the striped one and the blue devil) may present a problem in future when you try to introduce a new fish into your tank.
It looks like your tank can use a bit more rocks especially if you are going to add more livestock to your tank. As long as your bio load does not exceed the filtering capacity of your live rocks, you are going to be okay, provided that you don't overfeed your fish and export the excess nutrients in the water efficiently with skimmer, water changes, and/or macroalgae.