I am 28 Years old Female with a PWS on my left cheek, I have over 20 treatments between the age of 2-14 yrs old but ened up choosing to stop the treatments because I became comfortable with who am and stopped caring about what other people thought. Kids are cruel, I got slapped on the birthmark with a ruler by a kid at my borthers daycare because he didn't like the way I looked.
In terms of makeup, I would suggest Dermablend cover cream with the dermablend setting powder, covering just your bithmark and just a light foundation that matches the your skin colour and the dermablend. Dermablend when applied correctly works really well, so give it a trial.
I choose to only wear makep on special occasions, I work in retail and get a lot of comments from customers (good and bad) about my birthmark and there will always be the idiots out there that can't handle that not everyone looks "normal" They are the same kind of people who would make horrible remarks about a person with a disibility or a missing limb so don't take to heart what they say because they are not worth it.
I am getting married next year and having being together for 9 years, It is worth sourounding yourself with people who accept you for who you are and not how you look It is a great boost of confidence.
If you would like to get in touch let me know.