Frustrated with learning process

I wouldn't necessarily start learning all the "rules of thumb" stuff like the Sunny 16 rule. Don't get me wrong, they are useful, but it might muddy things up for you.

You are almost there. You need to decouple yourself from the camera's meter a little more. Yes, you can use the "middle" as a guide, but as already mentioned, understand that the meter can be easily fooled and you have to give the scene some thought and make adjustments accordingly.

Soon enough, you will begin to realize that certain situations will require certain adjustments. OK, snow, overexpose by at least a stop and a half, maybe even more. OK, shooting into the sun. I need to expose for the sky and use fill flash for the subject, etc, etc.

Yes, check your histogram, but don't be afraid of a little bit of clipping. You will learn that you can blow out the sky a little bit and still recover in post. If you aren't doing so already, shoot in RAW. What you see on your histogram will vary greatly based on what you are shooting. So just make sure you have good amount of information registered in the histogram and you should be fine.

One very helpful thing to know is how far you can go from the centered meter and not blow the highlights - this will tell you how much exposure latitude you have in doing your own adjustments while just using the meter as a rough guide. For example, if you do some test shots metering off of a brightly-lit sky, and the meter is two exposure stops above center, if those turn out to be blown to all-white you know you have less than two stops of exposure "overhead". If you try 1 1/2 stops and get a blue sky, then you know you have at least 1 1/2 stops of exposure overhead. That means you can do a scene that includes a bright sky and a darker area (say shade under trees) and expose so that the sky can be up to 1 1/2 stops above center and still get blue sky. That may or may not be enough to bring the shadow areas where they need to be, but it lets you know how much exposure overhead you have to play with before having to try something else. You can use the same principle any time you have a high dynamic range scene (from very dark to very bright) - knowing your camera's exposure overhead limit will let you know whether you can properly expose the entire scene without blowing the highlights.