Italy trip advice?

Me, wife, and 2 friends (all in our mid 20’s) plan on going to Italy this coming June. I have been working on an itinerary for some time now and trying to lots of research, but there is just so much to try to know. Wanted to post in r/ItalyTravel but I don’t have enough comment karma…..more of a reader. Below is my current plan. Please let me know if this seems crazy, is too packed, i am missing something or added something entirely unnecessary. This is my first time overseas, so I am not familiar with travel. We will be one bagging btw so traveling light. Also, we aren’t rich by any means, so I was hoping to reduce cost and have no idea how much this’ll cost…. Any help or advice is greatly appreciated!!

Day 1: Fly in early: MIlano: Brera, Giardini Indro Montanelli, Galleria Vittorio Emanuele II

Day 2: Milano: Duomo, Sforza, Parco Sempione, Chiesa Di Santa Maria Della Grazie 

Day 3: Milan to Monterosso

Day 4: Cinque terre

Day 5: Cinque terre

Day 6: Florence: Ditta Artingianale, Piazza Michelangelo, Vivoli

Day 7: Florence: Accedemia, Museo dell’Opera del Duomo, Basilica Santa Croche

Day 8: Pisa: leaning tower, cathedral, baptisterie; Luca; Duomo

Day 9: TBD: Tuscany? Wine tour? 

Day 10: Venice: walk the streets

Day 11: Chiesa di San Zullian (church service), basilica di san marco, Palazzo Ducale, Basilica di Santa Maria della Salute, S. Giorgio (bell tower)

Day 12: Murano: glass blowing; Burano: house seeing; train to Rome

Day 13: Rome: guided tour of Colesseum/Roman Forum/Palatine Hill, Arch of Constantine

Day 14: St Peters Basilica, Vatican Museums, Prati

Day 15: Rome: Trevi fountain, Pantheon, Campo Dei Fiori Market, Piazza Navona, Spanish steps

Day 16: Naples: Centro Storico, Dante, Plebiscito, Castel Nuovo

Day 17: Pompei: Tour, Mount Vesuvius, Train to Praiano

Day 18: Praiano to Positano, (path of the gods?), shop/explore

Day 19: Return to Milan (sleep near/at airport?)

Day 20: Fly out early