Ok. This might go pretty in depth by fewyn I trust you know what I'm talking about here.
Some slight mix/max things here to look at.
Take one point from Nature's Reach and put it into Improved Insect Swarm. Reasoning behind doing this is as follows. Range is HARDLY an issue in TOC right now, its rather confined and nothing should be ranged out from you except for the following. Icehowl crashes, faction champs if you're cycloning (you've got gale winds for that 4 yards though), anub if you for some reason get caught in the back away from him when he emerges.
Looking at the switch you'll net the following.
1% more damage on your wrath. During eclipse with your 2 piece t8 you should be critting wrath from 7000 upwards to 12,000. You're pushing another 70 - 120 damage per wrath, minimal yes, but according to your parse on Jarraxus you did 468,927 wrath damage X 0.01 = 4689.27 damage. It's a dps increase, minimal, but its a dps increase.
You've also got to look at your 1% increase in starfire crit chance. This like before, seems minimal but it really helps out in those rare chances that the rng fails miserably on the end of your lunar eclipse to push you into solar. Sometimes 1% means the difference between an extra cast and less uptime, or one less cast and more uptime.
Ok, now to move into your rotation.
I've found the best possible way to start the fight is this.
Target the boss, most bosses in toc have some form of start up. Figure out the time via dbm that the initial aggro starts. Queue up Force of Nature, about one gcd before the boss starts drop them right next to the boss. During that gcd start spamming FF. Reason I always go FF first is that you're not hit capped w/o it being up first. This means if you lead with IS/MF you could possibly miss and waste a gcd.
My general opening is this.
Treants > FF > MF > IS > Starfall
I get starfall up immediately to start procing my Nature's Grace to get my wrath casts going. Usually its one to three wrath casts and I'm up into Lunar already.
When it comes to my dots, the rule of not refreshing in eclipse is gone. Dots push up entirely way too much of your damage and having them up at all times means more buffs to the crit/damage of starfire and wrath. So do not hesitate to refresh your dots in the middle of eclipse. Just DO NOT refresh when they still have time left over. Clipping dots is bad and will result in a dps loss. I always let them fall off my target and then immediately reapply, just keep a watchful eye on squawkandawe.
Now that I said squawkandawe, I'm like 100% sure you have the addon but anyway I'm gonna say it for anyone who might be looking. Get squawkandawe and also wiseeclipse. I'm also sure you have this addon as well but I'm gonna explain both.
SQ&A - Tracks eclipse, MF, IS, FF, Innervate, Treants and your Trinkets.
Wiseeclipse - If you are casting starfire at the end of your lunar eclipse and you're SF cast time is more than the time left on the eclipse proc it will automatically cancel the eclipse buff allowing you to enter into solar faster.
You need higher uptime on your dots. Refreshing during eclipse will help this problem entirely.
Going back to the jarraxus parse your uptime for IS and MF is as follows seconds in uptime/length of fight in seconds.
MF - 198/233 - 84% uptime
IS - 171/233 - 73% uptime
MF is good, but could be improved, IS needs to be up over 80. Ideally 90% uptime on your dots is what you shoot for.
Get your tailoring up, lightweave proc will only help. Honestly that should be your first and most important thing to do.
You definately need more gear with crit on it. Don't be afraid to hover around 400 haste or a little below it. I try to keep it a rule when I'm min/maxing Arex that 400 haste is my goal, as near to it as possible w/o absolutely nerfing my other stats.
I'm not sure about your situational awareness but one thing I did with my placement of squawkandawe to increase my situational awareness and make it easier to not be scanning your screen is to place squawkandawe next to your character.
Much like you see here. As far as I can see you're entirely on the right track. Perhaps just go hit some practice dummies and run through about 10 mana bars practicing your rotations. I've always been a firm believer in the fact that the more you improve your muscle memory in your hands to easier it will be transitioning into raids when you've got to move and remember to hit buttons.
I think I covered the most of what I can cover. I hope what I tossed up here will help you out.