I too SI. I did as a teenager and then it stopped. It returned again after starting T. I do feel ashamed by it - particularly as all the literature seems to say it is something people younger than me do (I am 45) - that makes me feel that there is something doubly wrong with me. The main trigger to it is sui thoughts - I do try and do other things, but it seems to be the only thing that calms the intensity of the thoughts down - so I guess it is serving a purpose for me at the moment.