Hi Jenny

Sometimes people feel that nothing has helped so nothing will change............sometimes that may be true............but I much prefer to see it as nothing has helped yet
SO ideas................
It sounds like your psychiatrist was trying some desensitisation work with you, which can sometimes help a lot..........but just wondering if maybe it wasn't structured to meet your particular needs............maybe some easier stages could have been inserted, maybe the length of time between each stage wasn't correctly timed, maybe they weren't giving you the right coping/grounding techniques you needed to help at each stage...........maybe..........
So maybe that kind of work isn't necessarily something that won't work, if done differently..........and from what you've said you are a lot older now............so maybe done a different way it may be more beneficial to you.
So perhaps a return to a psychiatrist............or even a reputable therapist???
Although you'll find grounding exercises/techniques OR mindfulness online that could help too................
And..........of course..........an idea you might want to look into if...........could be hypnosis (from someone fully qualified, accredited and reputable).............sometimes it can help with phobias............so a maybe if............???
But until something is helping...........please try not to let it effect you going outdoors/doing things you want............a little checking might be able to help you find places you want to go/things you want to do where dandelions aren't present.

Alison