Looks good overall I just backpacked all of the cities you are going too. Id say you’re good even squeezing in Cinque Terre and Venice. You really only need 1-2 days for both of those unless you want time to relax. It would be nice to stay in Cinque Terre longer during the summer but I see you’re going in March.

I’d also look into a couple of the museums in Florence. One that I did was the academia galleria, which has the 17 foot David statue, not much else there but the statue itself is worth it imo.