I far as I have read you upgrade to T16 when you have 4 set only. 2p isn't worth losing T15 4p. I could be wrong though because this is assuming heroic T15 which you aren't using but I think the consensus is that even then the rejuv boost is a pretty big loss.
On another note Your haste is in a weird spot. The HBP are 3043 or 13163 the 6k-ish one was generally not worth it so aim for one of those mentioned 13k one is possible if for you and you lose no spirit in fact you can gain some at the expense of your mastery and int however the gain should still be more than the loss.
If you get the Mr. Robot addon you can copy paste this into it and you could hit the cap.
Code:
region=EU;realm=Nagrand;name=Sycamóre;faction=Alliance;spec=105;talents=213131;glyphs=54832,145529,114295,62970,146654,146656;race=NightElf;professions=Herbalism:600,Inscription:600;item=2:95244:0:467:r,y:4649,4649:76699,76699:4915:167;item=6:95242:0:467:y,b:4649,4649:76699,76699:4826:0;item=8:105787:0:493:0:0:0:4414:117;item=14:102247:0:493:r:4649:76699:4423:0;item=4:99172:0:493:r,r,r:4649,4649,4649:76699,76699,76699:4418:167;item=7:94273:0:467:r,r:4649,4649:76699,76699:4429:167;item=15:103875:0:493:y:4649:76699:4442:117;item=5:104753:0:491:r,b,p:4649,4649,4649:76699,76699,76699:0:117;item=0:95241:0:467:m,y:5031,4649:95345,76699:0:167;item=9:95240:0:467:r:4649:76699:4430:0;item=10:104773:0:491:y:4649:76699:0:0;item=1:103881:0:493:0:0:0:0:0;item=11:95139:0:467:0:0:0:0:0;item=12:94509:0:467:0:0:0:0:0;item=13:95817:0:467:0:0:0:0:0;
All in all take what I say with a pinch of salt I don't claim to know it all