Hello.
First thing is don't worry (easier said than done).
Is it worth ringing the nurse back and explaining you are hard of hearing and are unsure what she told you? If they say something you don't understand you can always stop them and ask them to explain - I know our nurses are much better than the docs at this sort of thing.
If that doesn't appeal, do you have a family member or friend who could ring on your behalf? As long as you give permission it should be OK. I have had to do this for my mum before.
The other option I have done is to go to go to the surgery and ask for a printout of the results. It is amazing how helpful they can suddenly be.
Good luck and I hope you are able to resolve the confusion.