Sensory issues and Social anxiety can each cause anxiety on their own, so when you combine the two, it often makes a bad situation worse. I have ASD, Anxiety, and PTSD, so I am speaking from personal experience.
I too am sensitive to light, sound, etc. Just being out in public in general is very stressful for me. So, you aren't alone there.
Whether you get an official diagnosis or not, anti-anxiety medications can help. So can learning to self-regulate, and Self-soothe in stressful situations. If you can't find a specialist, do look for someone with experience treating PTSD...a lot of the therapies overlap.
I'm just learning myself, so I don't have a lot of advice, but I hope it points you in the right direction.