Welcome to the forum, laxexquis! You'll find some very helpful folks here.
I've been shooting since I was a kid but I only started buying my own handguns and really getting into the whole pistol world in the past year or so, I was bewildered by the amount of options available (brands, platforms, calibers, etc). Don't try to learn everything at once.
Since you want a gun for home defense, it doesn't need to be particularly small or light. Light guns are nice to carry, heavier guns are usually more comfortable to shoot (less felt recoil). So you should be looking at full sized guns, if Glocks are what you like then try to find a range where you can rent a model 17. I'm not a Glock fan, but I admit they are good quality guns and not too hard on the pocket. My choice would be a CZ 75, it's a very good pistol which fits my hands better, its all steel construction gives it a nice heft and I find it more aesthetically appealing than other 9mm guns. Looks might not be important to some, but they are to me. If polymer guns are what you fancy, there are a lot of good ones out there as long as you buy one from a good brand (Ruger, Smith & Wesson, etc.) it should work well, and if it doesn't they'll stand behind their product.
Caliber-wise, I think you should try 9mm (9x19mm, 9mmLuger or 9mm Parabellum are other names for it). It's not the most powerfull round out there, but it will get the job done with proper ammo selection (a good hollow point, lots of options to choose from). Recoil is not an issue (especially with heavy service type pistols), ammo price is not too bad. I wouldn't go with anything smaller than that for home defense. The .380 caliber you mentioned earlier is basically a shorter 9mm, which is fine for a pocket pistol but you can do much better for a home defense gun.
You seem to be a little concerned about recoil, don't worry too much about it. It's something you get used to. Maybe after firing your 9mm for a while you'll want to give .45 a try, there's always time to get another gun.
I know you are asking about semi-autos, but don't overlook revolvers. While double action fire (shooting without cocking the hammer first) might be challenging to a beginner, it's not hard to master to a reasonable degree. It just takes some practice. They're easier to handle than a semi-auto, there's no way you can leave a round in the chamber or something like that. A .357 revolver with a 4" barrel (like a S&W 686) is a very good home defense weapon, if .357 magnum recoil is a bit too much for you at first, you can always use .38 special ammo in it (the recoil is basically the same as 9mm from a semi-auto). In my very humble opinion (I'm just a gun enthusiast, not a super operator or instructor) there's nothing like a good double action revolver to learn proper trigger technique.