I struggled with some jobs and can relate to your experience. My learning disability wasn't diagnosed until much later in life when I attempted college the second time. A wise professor guided me to the right people for testing and help. Since then, as Puzzclar mentions, it has been a matter of relearning how to work with it, (with the exception of lately), and finding ways of talking to people about it so they understand I need to work at my own pace. It may be slower, but is steady and will be done. None of us are alone in our strengths and weakness, we all have different capabilities, learning disability or not. We are better off asking for help when we need it, than to pretend otherwise. A job that does not understand this, sometimes it can be wise to find a place that does understand it and will work with us rather than tear us down.

What has helped me the most has been on working with a T on skills to apply to school and work, and has made a big difference. I don't know if this is an option but might be something worth considering.