hi honey *hugs* i'm so sorry your going through such a hard time atm. you're not alone though.
since self harm can become an addiction, it is really tempting and it is hard to stop. its important to know that you can though. it will take time and a lot of strength but you can make it.
do you have a psyc or counsellor you can talk to? have a good support system makes it easier to stop, takes a bit of the pressure off yourself and helps to get to the reasons behind why you're SI'ing because SI is a method of coping.
you mentioned your therapist. it there any way you can see her earlier than what you are? sometimes you can make emergancy appointments its urgent.
does your school have a counsellor you can talk to? if you dont want to be told on though it would be best to know about the level of confidentiality. for example, my school is obligated to tell your parents if you mention that you've self harmed or are suicidal or anything that involves harming yourself in any way.
in the meantime though have you looked at the distractions list?
http://www.recoveryourlife.com/index.php?categoryid=13
it might help to take your mind of how you're feeling for a little bit.
it might also help to have look at the self harm section here
http://www.recoveryourlife.com/index.php?categoryid=46
feel free to pm me if you'd like to talk *hugs*
soph.