#1, it is impossible for me to comment on diopters without measurements.
How do you see with the given diopters?
That may help us understand why the optometrist would suggest a 40% change in refractive power, in just one eye. It does sound rather alarming.
Also curious whether you are doing the course, and what further may be prompting this whole idea. I also don’t understand why you’d be reading with distance contact lenses. Are you not using differentials?