Perhaps you should look into getting medical hearings aids. There a some of those which can work with Apple devices too. It probably depends on where in the world you live.
Using headphones with hearing aids can be problematic. Large over the ear headphones can work OK, but with over-the-ear hearing aids (like mine) the headphones need to be larger enough to have clearange around the ear so that the microphones on the hearing aids aren't blocked. On-the-ear headphones can be quite uncomfortable with over-the-ear hearing aids as the press the ear against the body of the hearing aid and they also fead sound into the ear only and not into the microphones of the hearing aid.
Hearing aids that fit directly into the ear prevent the use of ear-buds, but probably work better with headphones than do over-the-ear aids.
@OP: personally, I would recommend that you investigate hearing aids. In the interim, you might find success with using an audio amplifier in circuit between the computer and the headphones. You should be cautious to not blast overly high volume sound into your ears as that could lead to further damage to your hearing. It's also possible that bone conducting headphones will work better for you, though that would need some experimentation.