Also whats the point of the Blue Damsel? They just get aggresive and territorial. So I reckon ditch that too. If you took away the Angel, Butterfly and Damsel you would have ten fish, which is a bit over but with a good skimmer and good bio-filtration (macro algae and LR and sand) is do-able. Make sure you get a good skimmer.
13 fish in a 75 gallon is too much. What kind of filtration will your tank have. Not trying to be bad person here but you`ll have problems with fish health and nuisance algeas due to excessive nutrients from a large bio load.
They grow quick enough. I think that you need to ditch either:
1) The damsel, butterfly and angel (and then be religious about PWCs and a really good skimmer.)
2) The Damsel, Butterfly and the 5 Chromis. <---- That's the best way IMO.