I added insulation around the fan housing and it made the problem even worse in the smaller bathroom
For now I am running the small space heater while taking a shower as I don't experience any condensation then.
One thing I should have mentioned is that the fan is installed on a 8 degree slant ceiling instead of a flat ceiling.
Could this be the problem?
Also, since the bathroom is so tiny, perhaps I need a stronger fan(more than 80 cfm), since the steam builds up very fast while taking a shower.
I'm all out of ideas, as I've tried everything(read the previous post).