Itinerary advice first trip to Italy

Welcome to the Forum. I'd suggest getting Rick's guidebook and reviewing his suggested routes, then maybe watch a video or two or three. Safe travels!

Cut that list in roughly in half and you are getting there! Ten to eleven days would be good for some of Rome and Florence, and a bit of rural Tuscany. You could do round trip Rome or Florence with that itinerary (or in one, out the other).
Or, you could do Rome and the Amalfi Coast and Pompeii, flying round trip to Rome or multi-city Rome and Naples.
Or, if the lakes is what has your heart, you could combine that with Florence and Tuscany, flying into Milan out Florence (or vice versa).
We all bite off more than we can chew when we start planning--the next phase is narrowing it down to what you can realistically enjoy.
Even after dozens of trips, I write it out day by day. If I have a lot of one and two-day stops, I keep working at my list.
You could spend the entire time in any one of those places and not see everything.

Did you buy plane tickets? What cities are you flying into and out of? You need to start in the south and work your way north, or possibly start in Milan and work your way south. Share your supposed day-by-day itinerary with us. Then we'll see if you are trying to cram too much in.

I have to agree with valadelphia. Your list is way too ambitious for the number of days available. You would basically be changing locations every other day, and with half a day lost with each change, would be left with only a day and a bit to actually see anything other than train stations or the view out of a moving vehicle.
Decide which 3 locations have the greatest importance for you, and leave the rest for another time.

I have not purchased airfare yet and I'm flexible on arrival/departure cities. I know this is probably too much but I was thinking (in no
particular order):
Rome 3 nights, Sorrento 2 nights (including day trips to Pompeii & an Amalfi coast town), Tuscany (Pienza/Montepulciano area) 3 nights & Lake Como 2 nights. If I cut one it would be Lake Como, but I would love to work in the other destinations. Appreciate your feedback.

You are not considering travel time--keep repeating in your head "I can go back," because you'll never get time back that was spent sitting on a train instead of enjoying a place. Also consider how many are in your group, their ages, who likes to sleep in or nap, whi likes long lunches, etc.
Two nights is not enough for Sorrento because Pompeii is a full day, and even if you only spent a few hours there, you have to travel back and forth and it would be a stretch to fit Amalfi into the same day. You would probably not be able to squeeze it in after arriving from Rome (though you could stop en route, that is not without complications and it's a place that should be leisurely embraced). Similarly, you would not want to take a long day trip the day you need to head north on several trains.
Google Maps can help you approximate travel times, but Trenitalia is a more accurate place to look.

How many nights do you have 10 or 11? Count your trip in nights for a more realistic view of what sort of time you really have.
it looks like just 10 nights?

For example- 2 nights in Sorrento is really just 1.5 days actually being there. It will take you half the day to get there from Rome.
Pompeii needs half a day or more. Amalfi coast drive is an all day affair- so you don't really have time for both.

From Sorrento all the way to Tuscany is 3/4 day- so 2 nights there is barely 1.5 days to drive around.

I'd actually say drop the Tuscany bit too because car rentals this year are astronomical.

If you can fly IN to Rome and OUT of Naples I'd recommend this:

Rome 4 nights- this is the bare minimum recommended time here
Amalfi town of choice 3 nights- visit other towns from here
Sorrento 3 nights- visit Pompeii and Capri from here
Depart from Naples- if flight is late in day you can stay in Sorrento on last night, if not stay in Naples

If you have to fly RT Rome then go to Amalfi/Sorrento on arrival- 6 nights there (note Sorrento is not on Amalfi coast)
Return to Rome for final 4 nights and fly home from Rome

ETA:
I'm just going to throw this out there- you can never wrong with the typical first trip to Italy- the Holy Trinity of Venice--Florence-Rome

With 10 nights
Fly In to Venice 3 nights
Train to Florence 3 or 4 nights- if 4 you could use 1 day for a day trip to Tuscany countryside
Train to Rome 3 or 4 nights-- if ancient ruins are important go to Ostia Antica- very close to and easy from Rome
Fly home from Rome

Either go Rome and south or Rome and north; otherwise, you'll be moving around a lot.

I would suggest not biting off too much with the first bite. You have a ton of movement and your 10-11 days will be eaten up with transportation. I'd suggest dividing this into two trips doing Rome, Naples, Pompeii, Sorrento, and the Amalfi Coast in one visit and save Florence, Sienna, Milan, Lakes, etc for another time. I jammed packed a few itineraries before and had lots of fun but always left feeling like I didn't give enough time to each place.
There are a million ways to tackle your itinerary. I'd want to know the number of days you plan to spend in each place before deciding the best route.
Best wishes!

Mid to late May is pretty late in the year to visit the Amalfi Coast, and Pompeii has zero shade so it be a hot day in the sun - and you need a fairly large part of a day for Pompeii.