i can understand your concerns.It would be better if you would have told me which type of psoriasis do you have but for such long history i would suggest its chronic plaque psoriasis
Now coming towards your question, i can see some prviouse answers of doctors that psoriasis can be treated permenantly,which is totally wrong.There is no permanent cure although there are some treatment options that show promissing results to control the disease and there is still lot of research going on.
So there is no such thing as to stop it forever,but the good news is its not lifethreatening,not contagiouse and as i said it can be controlled very well.
I also dont know which treatment options have you tried because sometimes several medications and treatments can be tried to reach for the most suitable one.Sometimes many medications and treatments are tried at the same time to gain maximum benefit.
If you say that you have tried everything then i would suggest narrow band UVB and Also PUVA therapy
,they are really effective in chronic plaque Psoriasis.
I think it will need a long discussion with you to explain all these options,i hope you can understand my point.
thanks very much and all the best.