Help with depersonalization/derealization

Hello there, my name is Alex and I am from Central Europe Romania. Last year, around this time, I went to a friend's house where we smoked pot ( this was the second time in my life when i use weed ) and I got a severe panic attack, with symptoms of depersonalization/derealization. This has been going on for over a year and honestly I do not know what to do. I feel hopeless. The symptoms are constantly there, and it got to a point where I am barely functional ( thanks to my parents I can take care of basic needs ). I tried therapy , but nobody seems to have a clue about this condition. Do you have any idea what can I do ?