I'd say your bioload isn't quite as full as you think it is. The idea that a tank can be 'full' bio-load wise is a bit of a myth - bacteria will just keep multiplying and balancing the tank.
You might notice higher nitrate and phosphate levels, which can fuel algae and cyanobacteria growth. Territorial limits are definitely something to watch out for though - it's easy to overstep those boundaries in a smaller tank like yours.
Is the tank full?
Re: Is the tank full?
Your tank's not over capacity in terms of bio-load, but I'd say you're getting close to overstepping territorial limits. Overcrowding tends to stress fish more than the increased waste they produce, which can still be managed through regular water changes.
Re: Is the tank full?
"yeah, but my current fish are on the larger side, right?"
Re: Is the tank full?
You could still consider a small fish or two, like a member of the goby family, but just one or two, not a whole school. If you do decide to get two, just make sure to space out the purchases by a few weeks so your nitrifying bacteria have time to adjust to the new bioload without getting overwhelmed.