Life steal is missing and something you'll need for higher MP. IAS is also not in the right area IMO, too low.
Simply upgrading your weapon emeralds would add 60% CHD to your build. Upgrading your other emeralds (including replacing the amethyst in your pants) would add close to 100 dex. Combine the added dex and CHD, your DPS would go up by several thousand.
You need to find some IAS and LS though. Perhaps a two piece nats (ring and boots) along with a new LS off-hand weap.
Upgrades depending on what you wanne do. If you wanne farm like mp3 or 4 with upcoming patch i would get:a new offhand and a new rare ring.
A ring with dex, decent avg dmg crit chance and crit dmg. is like max. 10mil for a decent one. A new offhand with same stats(maybe a bit lower dps) but lifesteal on top should help quite alot on higher mp. 400 loh is for sure not enough for anything above mp2.
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Words of wisdom: Don't follow the advice of people who won't have to deal with the consequences.
The biggest upgrades at the moment would be a decent nat's 2 piece and also getting some sustainability through lifesteal(5%+ is ideal).
The stats on the nats boots should be 180+ dex, and 40+ of your stacking resist, the other rolls are pre-determined. On the nat's ring I would aim for a ring with your stacking resist, crit( if you have 50m to spend), crit damage ( if you have 25m to spend), if you cant get 1 of those damage modifiers on your ring I would look for something with a high average damage roll xx-xx damage( that should run 5m gold.
Weapon Wise : I would get a rare weapon with 1000+ dps, dex, crit damage (over 70% or a socket) and lifesteal. ( You won't be able to get a weapon with a socket and crit damage unless you have a large budget and assuming you don't, so get so to elivate costs you find a weapon with his base crit damage or something with a socket, but since most budget monks don't get over 70% chd gems, I recommend ones without sockets and high base crit damage)
Offhand : Won Khim Lau(dex lifesteal socket) or a EF with chd( 60% + ) and a lifesteal