The interpretation from/by the doctor that vulvodynia is a mental issue is unlikely. The burning is more likely hormonal issue from birth control usage or oxalate sensitivity (unlikely).
Good resources to begin to research further to find a solution are:
https://www.bodiespodcast.com/resour...de-1-sex-hurts
https://drbrighten.com/beyond-the-pill/ (I'd recommend this first, easier and more likely to solve issue)