Diagnosed then forgotten

I was diagnosed 4 years ago at age of 26. I was tested and diagnosed then that was it goodbye and no help offered whats so ever to cope from the nhs. There seems to be no one who specialises in autism and ptsd  therapy work in the nhs. I cant work a job and hardly leave my house and dont feel like im living. I struggle to communicate my needs and just feel like ive been forgotten. 

Is it common to be diagnosed by nhs  then just given no help?