Just my opinion of whats nice and simple in photography, buy more primes first ( see you've got the sigma 35 1.4 which seems a great lens) it will make you start thinking about your shots and composition better, also help you choose the right lens for a shot. Now even if the flexibility of zooms for some jobs still is needed, start shooting personal work like portraits with the primes - i'd say 50 and 85mm are the first ones or maybe the 135mm F2L, also the 100 2.8 macro is great for portraits and macro.
Also if portraits are a big part of you're photography then definitely 2 or 3 proper flash monoblocks - even cheaper elinchrom D lites or something and a few modifiers, softbox, brolly & beauty dish will make you work have a new life, camera & lens is just half the equation in my eyes but then I use flash a lot to light scene & portraits, and thats where a lot of my style or technique come from.
With all you're zooms and the fact that maybe you're wanting to get a longer zoom, can I hazzard a guess that you like capturing moments and that side of photography? Maybe try looking at the other side a bit more.. ie making or controlling an image with a extremely considered view / composition and then begin working on the lighting and experimenting of what you do with lights (studio flash) and that will open up possibly a whole new way of thinking and working. TBH i normally get more excited about a new flash head or certain modifier than a camera or lens as I can do a lot more with it.
Hope this helps!