Help me with my 3 week female solo travel Europe itinerary!!

This is my first time traveling overseas (from the us) and my first time female solo traveling. I want to spend majority of my trip in Italy! I am just looking for tips and pointers. Also, I need to know if my trip is too many cities or too fast paced. Please let me know! I want to have some coastal vibes, history feel, and a location to relax. This is what I’m planning to do -

*Fly to Prague (most affordable)- 3 nights

*Fly to Milan and train to Lake Garda- 2 nights

*Train to Florence- 4 nights

*Train to Amalfi- 3 nights

*Fly to Sicily- 5 nights

*Fly to Nice, France- 3 nights

Please let me know how your experience was female solo traveling to these places. Is there anywhere I should take off or extend?