Sorry to see you join this exclusive club, @Kathryn2412 .... the one you didn't expect to join .....
I always react badly to anaesthetic but it just makes me throw up.
The 'whistling' is a little concerning .... are you able to take a deep breath without hurting? Lots of shallow breathing can cause congestion in the lungs, which can lead to pneumonia, hence the need to cough it up, if possible .... Definitely chat to your Breast Care nurse, as this has happened within a week of your surgery - and should be addressed xx
take care & all the best with your recovery.