Chris, I am not really sure, but I suspect you need to thin your paint a fair amount more. Also, check to see if paint is accumulating in the nozzle, on the outside where it leaves the orifice. That happens sometimes on my Badgers with some colors. It will accumulate there and then when it gets carried to the model it will make a splatter.
As for air pressure, since you don't have a gauge, start from the low side and gradually increase the flow until you get just enough for the paint to flow. The thinner your paint is the less air pressure you need. Which air brush are you using?
Another thing that can change the air flow you need is if paint has accumulated inside the air brush. If even the slightest amount of paint has built up there it can restrict the path and increase the air needed, and this is bad also because it will foul up the spray pattern. I run lacquer thinner through my airbrush frequently to avoid that. Very occaisionally I will disassemble the nozzle and soak it in lacquer thinner, and wipe down the needle. As I have learned to spray with lower pressures and thinner paint I have had less need to do that, and I try to avoid it because those parts are very delicate and easy to damage.