Putting the closet behind you will work out better for symmetry of mix position - draw your room and draw in a grid - evenly divide all dimensions (includiing height) by 2,3,4,and 5. With the exception of having your head centered left to right, don't put either your head or your speakers on ANY of those grid lines - even 3-4 inches off will help. The goal here is to NOT have either speakers or ears exactly where your room resonances (called nodes and anti-nodes) happen. These will skew the perceived response at the mix position.
You can't mix at low volumes and expect the mix to be balanced in frequency response - if you don't already have one, stop at Radio Shack and get one of their Analog Sound Level Meters (around $45) - set it up in "C" weighted position, fast response, and keep it on the desk while mixing. Set your levels up so you're getting an average of 85-90 dB during playback. If you turn up the kick drum, check the sound level and readjust it back to 85.
If this doesn't make your mixes "translate" better, you may need a subwoofer or more room treatment. Maybe both... Steve