Am I overstocked

[Ruth]

I think you are fine and can easily add more fish particularly if your skimmer is able to keep up with the additional load of bigger fish and you have sufficient live rock for biological filtration.

[rickjames]

No I don't think you are overstocked at all. With a large skimmer like you say and a mature tank I'm sure your system will not have any problems with the small increase in bioload.