The problem with trying to save weight by changing components is that weight is distributed all over the bike. Each replacement only gives you a small, incremental weight savings. You can save a lot of weight if any of the components are steel, but I don't expect that any of yours are. The biggest place to save weight is tires and wheels, but unless you're starting with something really heavy you have to spend a lot to save a significant amount of weight.

I'd start by figuring out why you want to save weight. A lighter bike can feel sportier, but unless it's a lot lighter the actual performance difference will be miniscule. A heavy bike definitely feels more burdensome to ride, though, and if you have to lift it a lot (carrying it up stairs for instance) that's a good reason to care about weight. Where the weight is also makes a difference.

My main commuter bike is a 2013 Kona Jake that I've customized significantly. It has a nice carbon fork and Ultegra level components, but it also has disc brakes, a rack and fenders. Before I strap on lights and bags it weighs about 24 pounds. When the weather is nice, I'll often ride one of my vintage steel bikes with no rack and no fenders, which are mostly between 21 and 23 pounds. My workhorse vintage bike is a 1982 Specialized Sequoia with a front rack and fenders, which weighs pretty close to 24 pounds. There's not a huge difference in the way any of these bikes feel, but even between the Jake and the Sequoia which weigh nearly the same I feel the difference because of how the placement of the weight affects handling.

My suggestion to you would be to focus on tires. A lot of commuters get hung up on puncture protection and so use heavy, stiff tires like Schwalbe Marathon Plus. That's a reasonable choice, but for distances like you're talking about it's also a significant burden. Switching to something like a Continental GP 4 Seasons or a Conti Grand Prix 4000S II will make the bike feel a good bit zippier, and I've found both of these tires to provide reasonably good puncture resistance. The 700x28 GP 4000S II is my favorite tire right now.

If new tires don't make you happy, then I'd definitely be looking for a different bike.