Maybe you're a tactile or sequential learner? There's "Method of Loci" or even "External Vocalisation".
You're capable of reading and writing so that's 100% evidence you're capable of learning - and being able to perform a sequence of tasks allows you to understand how to perform an action correctly.
Let's go with that and try external vocalisation. Many would trade the noise in their mind for silence and the ability to focus clearer on a task.
When you're working on a task, since you lack an internal monologue - vocalise it instead, it doesn't need to be audible, even moving your lips quietly should work as this will tap into your motor cortex which is highly tuned for performing sequential micro-actions.
Try talking to yourself about the steps you must take to get something done and see how you go.
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Of course this is something you can try at home but following up with a few medical advisors will also open up other avenues for course correction if you feel this is becoming a real problem.