Hello there,
Day dreaming is harmless and normal.
but, Like you put it across, if it's 'maladaptive', it has to be evaluated in detail.
You also posted that the day dreaming increases when you are stressed out. It looks like this maladaptive day dreaming has got something to do with how you cope up with stress
Next Steps
you will definitely benefit from a consultation by any mental health professional, preferably a Psychiatrist
good luck