I'd avoid the .380 caliber entirely, due to the price, given that if you are going to practice with your Carry gun, you will spend more on ammo over the course of owning it than you did on the gun..... not all at once mind you, but over time.
Choosing a 9mm over a .380, you will save enough over time to buy another gun ..... not all at once, but the $2-$5 difference in price per box of ammo adds up.
Do the math.
Also, during the Great Election Induced Ammo Shortage of 2008-09, .380 ACP got downright hard to find, sometimes.
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."