Hi and welcome,
I understand that you are worried that you might have PPMS, but it is very unlikely that what you are experiencing could be something like PPMS, because PPMS is a very slow developing type of MS, so it's more typical for someone to be in the 40's before their decades long slow deterioration becomes more evident and or disabling.
With you only being 23, having experienced a lot of symptoms over too short a time frame of a year to 3 years and you also have bilateral hearing loss, and whilst hearing issues can be associated with MS, it is classed as one of the rarest symptoms of MS, so I honestly believe a neurological condition like MS is not very likely.
A vestibular disorder would explain some of what you've experienced but it wouldn't explain everything, unfortunately i honestly couldn't take a guess on what medical condition you 'could be' dealing with. Bilateral hearing loss in someone of your age group i think is more commonly congenital, loud music exposure and or headphone behaviours and some viral infections but i'm sure there are other explanations, although i'm not familiar to help point you in any particular direction, sorry.
I have PPMS. First off in the US you have to have been diagnosed for a year before you are diagnosed with PPMS. The way PPMS usually works is you notice your running gets harder, then you can't run at all. Then you can't walk to well. You usually have about three lesions in the brain then possibly some on the spine. Because the damage is more in the spine you usually have more mobility issues. It is diagnosed in the 40's or 50's. Between 10-15 percent of people with MS have PPMS. You definitely would have lesions on the MRI. What you describe could be MS but more likely it is something else. In the US it takes years most of the time to get a MS diagnoses. If you have no MRI abnormalities it is hard to be diagnosed. Mostly a doctor if they suspected MS would see you every six months.