The first first first upgrade for you is definitely Life Steal. Just by having 2.7% LS you are able to advance to MP4 easily. Rest of you gear are fine, for up to MP4, your armor is overkill, HP is overkill, AR is good, real DPS is good too. Alternatively getting 45+ LPSS and swapping GP for Transcendence works too. But LS is pretty much needed for MP6 onwards.
Please also note that the more offensively you're geared the faster you die from reflect damage affix in higher MP if your sustain stays the same. So before improving any
offensive stat you need to improve you character's sustain first.
Skill wise, you should try to include Dashing Strike. It's basically Serenity without cooldown, with enough practice. Breaks free of Jailer and avoids ground hazards, and cannot be frozen while dashing too.
Most of the people that can handle higher MP not only they have better gear, but because they play for longer and hence more skillful. So take your time, enjoy the game, or, play a lot more :D
Lastly if you want to improve your DPS without spending a dime, there are already plenty of alternatives posting on this forum this week alone, they are all better than the current cookie cutter. Then of course I'd recommend my Tiger Strike
Way more DPS, way more sustain, way faster farming speed ;)