Wha do i do??? (Social Anxiety vs Asthma!)

With the new enforcement on masks on 24th July I'm worried which is going to affect me the most...

1) Wearing a mask and it restricting my breathing/triggering my asthma or

2) not wearing one and having to put up with all the dirty looks and snide remarks from everyone such as 'She's not got a mask on, why's she not wearing a mask?'

I am autistic too and I do have a sunflower lanyard but I've not got an alert card or anything. I'm wondering what form of proof is official and accepted so that I don't get a fine if I can't wear one because even the sunflower lanyard isn't recognised everywhere.

Do I get a letter from my doctor about my asthma and autism or will my autism diagnosis letter be enough proof? My autism itself isn't stopping me from wearing one because I'm ok with the sensory side of it but I'm worried about my asthma. 

Advice please, thank you in advance.