I currently don't do any professional portrait shoots but when I move out I am considering giving it a try to help my income. The screen and calibrator will be important because I know for a fact my prints don't match what I see on my screen all the time (my screen isn't even an IPS screen). I think if I do manage to get the money together to buy the 85 1.8, I would consider upgrading it eventually to the 135mm f2L.
The 135L is my favorite people and theater lens, but you will definitely want to have a 50-100mm lens on hand for anything wider than 1/2 body shots indoors. Your 100mm macro may even be a bit long for that use (IME 15mm is surprising significant between 85 and 100 - a good step back/forward you may not have room for). That said, I think you're on the right track keeping your 50 and 100 and pursuing other priorities for now.