Without limiters on the master, does your levels go red on the master?
If yes, this may be clipping the output and making it appear like there is extreme limiting happening, and quite possibly distorting the sound as well.. hard to say.
Without anything on the master, I have to assume you're in the red, or compressing individual instruments too heavily, removing dynamics.. but even with compressing individual tracks, there shouldn't be the appearance of limiting on the master.