Hello jen, and welcome to the forum,
I think your schedule looks pretty good but if you want to focus on Rome I would slide some days down to the Rome end of your trip.
Florence certainly deserves a number of days and couple of days in Bologna is easy. Most people here vote for Parma over Modena or stay in Parma and see Modena as day trip. (I'm doing them for the first time next year and staying in Modena because there are places I want to see from there.) I can 5 nights, 3/4 nights, 3 nights being a good schedule and shifting a few days into the Rome end.
The flight days to Sicily require you to stay at least a week, I think. Then a few days in Naples and then Rome for a week or so on the way out sounds good. Rome will eat as many days as you can throw at it. Even with a week there will probably be things you won't get to see.
All of this is inter-city stuff is easy to accomplish by train with the possible exception of you special visit in Sicily. If you can fly into Bologna or Pisa and maybe even Venice you can jump right in. If you fly into Milan or round trip Rome you may have to take a night before travelling on. Some people power onto Florence after landing in Rome but I fly from the west coast it's too long for me to do that. A quick check doesn't show any direct flights to Rome from Boston (summer schedules may differ) which means it should be easier to fly into the north and out of Rome which I would recommend.
A couple of notes: Most people here track nights in places where 4 nights equals 3 full days since it is clearer than what some people say they are spent "2 days" someplace. And it is helpful to track nights of lodging booking as well.
Bologna and Modena are actually in Emilia-Romagna rather than Tuscany. For travel planning it doesn't matter but Italians will call out for misidentifying their region since they are fiercely local.
Hope that helps, come back with city specific questions as they come up,
=Tod