stick to welter.
Most MMA MW champs have 70+" reach. Unless you favor the ground game, or you're a real scrappy striker (good chin, not afraid to get in someone's grill, excellent footwork, great head movement) guys are gonna pick you apart from a distance. A.Silva has a 77" reach.
If you are really 16%, you dont have too many #'s that you can lose. 225@16%=36#'s of BF. GRADUALLY taper off the cals, and protein. Maybe a 200-300cal/day deficit. Might wanna get with someone way smarter than me to give you advise there.
If I were you, welter (170# area) is where I'd set my target. Good job being 225@16%, but there's no way to fight in the '70's without losing lean mass. Most MW's walk around 200-210, which you're already at so fighting MW isnt a horrible idea. I dont know what your skills are, but you'd rely more on technique at 185 than you would at 170. You'd out-muscle people at 170 with technique being equal I think.
If you're fighting ammy, dont worry about it too much. If its a pro fight, then take it very seriously, especially in your nutrition. But hey, its your fight record.