You were skinny thru all your life. I understand you - I weighted 63kg (138lbs) with 182cm (6ft) when I was 25 y.o. I found my solution even though all my friends and relatives told me I could never change.
I know you tried a lot by now. And I am not going to give you perfect advice - because there is no universal solution. You have to find your own way.
So here you can chat with others working on the same problem now. Share your attempts, discuss achievements - find your own way!