Hun, I'm going to advise you this now, because I wish someone had said it to me when I was 12. Speak up about how you feel to someone, family member, friend, teacher, GP. Seriously, speak up and get those feelings and thoughts out of your system. Get help. SIing, suicidal thoughts, they aren't normal really, and I understand you've been doing it for some time now, but you really do not want to continue.
It doesn't matter if its one day or one hundred, its still a great achievement if you can go any time at all without cutting, so be proud of yourself! You know that you can get help here if you want to stop cutting. I think its always something to consider. There are so many alternatives to self-harm that are just way less harmful (mentally and physically) and are worth a try. Have you tried distractions, squeezing ice, drawing on yourself with red pen instead of cutting? Write things down or talk about it whenever you feel low.
There are supporters here on RYL who can listen to you and talk to you if you need them. Check them out here on the forum,
Live Help, E-mail Support,
Open Topic Support Forums,
Specific Support, Advice and Recovery Forums., and
Support Chat.
Other options are speaking to
Samaritans [UK] for example, or another available helpline.
Its strange coming to a new site where everyone has their groups of friends already, but so many RYLers are like you, wanting to speak to someone but don't know how. I suggest checking out Chat and see who's available there to talk. By replying to some of the General threads, you might get to recognise screenames, avatars, get little conversations going...its all good. You could randomly PM some people, ask them how they are, it might make their day and they might reply :)
It might take a while to adjust and get to recognise people, but this is a really friendly community, so never be afraid to shout if you aren't OK or want to meet some new faces.
Take care of yourself hun
xo