I think you’re right around a perfect bioload for the size of aquarium, but you could add another small fish or two and still not be dangerously overstocked. It just depends on what you want to keep in the tank, what kind of filtration you have, and how much/what kind of live rock you have. If you’re mostly interested in keeping softies with some LPS, you could add another fish or two, if you’re planning on a mixed reef or SPS dominant tank, I’d probably stay where you’re at (but this depends on how effective your nutrient export is, if you have a productive refugium, or can effectively keep your nutrients in check through water changes or carbon dosing, or maybe all of these methods, you could probably still add another small fish or two). There are just a lot of factors to think about and what your plan for the tank is.