Like other posters here, I think your description does not sound like you are particularly slow. But even if you are, slowness is something that needs to simply be worked on--not despaired about. As my adviser in college used to say: turn your weaknesses into strength.
That may sound ridiculous when it comes to something like being slow to grasp concepts. It is something I have been struggling with as I've taken to studying Calculus almost 15 years later than most people. But I have been greatly encouraged by some of the things Barbara Oakley has to say. Here is a quote from chapter 12 of her book A Mind for Numbers, "Learning to Appreciate Your Talent":
If you are one of those people who can’t hold a lot in mind at once—you lose focus and start daydreaming in lectures, and have to get to someplace quiet to focus so you can use your working memory to its maximum—well, welcome to the clan of the creative. Having a somewhat smaller working memory means you can more easily generalize your learning into new, more creative combinations. Because you’re learning new, more creative combinations. Having a somewhat smaller working memory, which grows from the focusing abilities of the prefrontal cortex, doesn’t lock everything up so tightly, you can more easily get input from other parts of your brain. These other areas, which include the sensory cortex, not only are more in tune with what’s going on in the environment, but also are the source of dreams, not to mention creative ideas. You may have to work harder sometimes (or even much of the time) to understand what’s going on, but once you’ve got something chunked, you can take that chunk and turn it outside in and inside round—putting it through creative paces even you didn’t think you were capable of!