You're 22 and about to travel abroad. I know you're well schooled in the subject of travel. But I'm still your mother, and my $$ are paying the tuition to send you there, so I need to share. (OMG, did I just pull the "I'm paying your bills, so listen to me" card? I'm turning into an old fart!) But anyway, daughter, you'll ignore what you don't like and you'll choose to follow what you do like, so we're even. Okay? Here goes.
The packing list has suggestions for what to bring and what not to bring. Your friend's comment that "this must have been created by a guy" is not so far off. It doesn't address womanly packing such as, well, bras. Feminine products. (Did I just say "feminine products?" OMG, I'm turning into my MIL!) That kind of thing. I'll add a few simple and frugal suggestions.
Bar soap. You can use a tiny bar of soap to wash yourself and wash your clothes. Scrub underwear or bra, rinse it, then let the garment dry overnight. (Did I just say garment? OMG, where did that come from?!) A small Tide to Go pen will be handy, too. Wearing clothes three or four times at least will save you a lot of space in the travel pack, and if you can clean them in a hostel's sink, each piece will go farther.
You thought you packed lightly for France in your senior year. Honey, you took a huge suitcase and packed it to the brim for a two week trip. This journey is three weeks long, and you'll be carrying a much smaller backpack and a heavy camera bag. You dress in layers, I know. But can you re-use those layers a few times? Bring one tank that'll go under everything. Okay, two. Then the tees or the button down shirts. Keep it plain, simple, tops that'll go with every pair of capris and pants that you bring.
Pants? You'll be in Italy. In May. Should be warm, shouldn't it? Can you do without denim altogether? It'll keep your backpack lighter, and you'll be able to feel dressy if you need to without carrying extra trousers. (Did I just say trousers? OMG, I'm watching too much What Not to Wear!)
Shoes: I won't go there. You're the shoe queen; you'll choose what you'll choose.
Adaptor: definitely share with a friend. If you can borrow Grandma's adaptor again, maybe a friend will carry it for you since you'll have your heavy camera. You can share pics with the group after the trip in exchange for that favor. It's not bragging to say your photos will likely be better than anyone else's.
But in general, dear daughter, I know you. Your tendency is to procrastinate, wait until the absolute last minute, and then end up spending more than you need to or packing unnecessary miscellaneous junk. So if you take no other advice, take this one: plan sooner rather than later. In fact, do it NOW. (Did I just say NOW? I meant it!)