My first comment is, if you feel that your hearing is impaired in one ear,then it is...whatever the Audiologist has to report.
The high pitched noices are significant particularly if they are in the impaired ear.
March 2021 is a long time to wait and if you can afford to go privately it may well be the best £150 that you will ever spend.
How old are you and what medications are you taking?
Have you ever been exposed to noise or worked in a noisy occupation?
Do you have any dizzy spells or unsteadiness?