3. b3 is not principled. You might want to develop your Bishop to g5 (rather than b2), so b3 kind of commits you to developing your Bishop to b2. Also, the Bishop on c4 lacks mobility with the light-squared pawns on a2, b3, and c2. Here is how a typical Italian game is played:
Just asking because I usually get something like this where i literally go out of the book in the first few moves: