You are doing astounding art here (I don't want to associate the word work

).
We need to talk about your paint viscosity and air pressure though....
What I am seeing on your spraywork is suggestive of poor atomisation or lack of pigment emulsification.
Different colours are actually different to spray because of the pigment and white is the worst...always.
The general approach I would suggest testing on another hard surface (specifically hard surface not cardboard or absorbable) is the following:
Viscosity / air pressure / distance are what you use to control spray quality...
a thin low pressure up close for super fine lines if pushed too hard with too thin or too high pressure will fish-eye (insufficient pigment), or blow around (air pressure).
a thick paint with insufficient pressure will not atomise correctly and will look spotty.
Spray too far away and your paint will dry before impact and look powdery.
Can you see the combination of these factors in play? It's infinitely variable *within the capacity of the paint and your airbrush*.
Some basic guidelines I suggest for comparing to your current results:
1. Paint well shaken and mixed with reducer to appropriate consistency. Even paint able to be sprayed out of the bottle can be improved with reducer to get pigment to emulsify properly (so leave it for about 15 min after mixing) and often will flow MUCH better at reasonable air pressure.
2. The distance you paint is going to be controlled by nozzle size because the paint is in a circle not a fan, and naturally a smaller area than a spraygun style paint tool. A fine nozzle needs to be closer or slower moving.
3. Adjust air pressure so you are getting finely atomised paint that flows cleanly and hits the target wet.
A guide to air pressure is often available with the paint in online manufacturer guides.
4. Trigger control, angle and distance are the art of airbrushing. For general stencil work wanting even coverage spray past the area in overlapping strokes - this avoids hot spots from pausing.
Learn to be able to turn off hte paint with the trigger while keeping air flowing.
An exercise for this is 2 vertical lines about 10 cm apart. Starting before one line you want to spray accurate straight lines to make a ladder. Keep the air on and start/stop the paint at the veritcal lines - no overlap and no short stops. It's pretty hard to do initially but helps you develop trigger "feel".
Createx have some amazing tutorials online. If you can search for their airbrush tutorials not so much the spraygun ones you will get a TONNE of info that has helped so many people.
Also Drew Blair... he is one of the foremost airbrush artists in the world and publishes a lot. He is more a photographic artist but the skills are all the same.