Like another member said it is a bit of a grey area but from my personal experience and what I know, if it (1.) Leaves a mark for more than a few minutes (ie scar), (2.) You are doing it to quit feeling something or to cause feeling of something than it is likely to be SI. Before I started cutting I would pitch my arm very hard and feel lots of pain when upset or angry and sadly it led to other behaviors in the future. Not saying that will happen with you but it is important to stay aware of why you are doing it. I too have a form of PTSD from several past traumas (which might trigger people so I wont get into it) and one of the reasons I used to harm myself was to stop the flashbacks and panic. Like someone else said it is worth mentioning to your therapist, they may be able to offer you some help in coping. Best of luck!