[r250r]

"... bad at problem solving ... really not smart ... slow, forgetful, concepts never seem to stick, ..."

So you don't know everything, and you realize it. The people who are the most stupid are those who are certain that they know everything that matters. So you're not stupid.

You want to better yourself. Again, that's good. You're motivated.

You mention some subjects you wish to learn more about. I'd ask for advice on which books are best. Buy those books and skim through them. Keep the book(s) nearby; when you get into something that you need to know more about, crack the book open and read the section. That way you can implement it as you read about it, and you'll understand it far better.