Why doesn't my freshly painted door fit back in the frame?
You say


  The new coats of paint are not too thick so it's not the paint job.


and this is a common misconception. Yes, it looks like the paint is negligibly thin but it actually adds up. When a door is constructed it has size that allow for painting it once, maybe twice, and then a new layer of paint will prevent it from closing.

You should have cleaned the previous paint off the door edges.