Wow, thanks everyone! So I will fill in some of the gaps and answer some of the questions everyone had.
I am traveling to Italy in 2 weeks. My airline is SAS. I am taking only seasonally appropriate items, no "just in case" things. I will wear jeans and a sweatshirt onto the plane, so I will have those as my just in case items. I'm also planning on bringing a light jacket, but it's very light, so I just figured I would throw it in my bag at the end.
My luggage is 7.25 lbs/3.25 kg. It's not the very lightest that I found, but it was amongst the lightest, and I wanted hardside, and I also wanted lockable for security reasons. So...considering the parameters I was wanting, this one was the lightest one that fit the bill in my budget.
Side note- not to go off on a tangent. My sister and I went on a trip a few months ago, and we shared a carry on (domestic, so weight was much more lenient). The weight limit was 40 lbs, and the luggage itself weighed 7 lbs. That gave us each 16ish lbs in the luggage. So, I really thought with that experience, this wouldn't be a problem at all. Although that trip was a bit shorter, I also packed some much heavier items. So, essentially, I would just have to cut my packing from that trip by 3 lbs, and I should be good. That's what I expected anyway.
My first pass was 20 lbs/9 kg. After I took my bottoms cube out, it came to 17 lbs/7.7 kg.
Someone had asked about the scale, and the scale is in both lbs and kilos, so...even IF I (or more like Google) got the math wrong, the scale shows it in both measurements.
Someone also mentioned 5 bottoms being a lot. Here's where I land on that: I have one pair of shorts that will go with several of my tops, very multipurpose, which is why I packed it. I have a pair of bike shorts, which I will be using under my skirt/dress, but it can also be used generally too. Again, multipurpose. I have a pair of Under Armour shorts, super super light, the lightest pair I own, which will primarily be used for sleeping, although I could use them in a pinch. (And I am now realizing I didn't pack any tops to sleep in so...guess I'll just wear whatever I have on at the time) Then, I have the two pairs of leggings, which aren't really heavy, but I may wear one under my jeans on the plane if I have to. And, as mentioned above, the bottoms only comprised 1.3 kg, so I don't think they are the problematic part of the equation.
As far as having almost one complete outfit per day...well...yes. But, you see, I typically wear 2-3 outfits a day. So, having even 1 outfit per day is already a massive downsizing for me. And, I know with me being out and about, doing a ton of walking, the hot sun...I am going to want to change clothes. I just know it.
Yes, I am allowed a backpack. Which I can use if need be. I was just hoping to keep it as clean and clear so that I have everything available during my journey as possible.
Update: so I took out 4 items of clothing. I was able to get the skirt and dress into small packing cubes which fit in my backpack nicely. I took out leggings, as I will likely wear them on the way. I also took out a shirt. I consolidated all the clothing into one packing cube. It didn't move the needle much. I am now at 15 lbs/6.8 kg.