First off, I just want to say that (as someone who struggled/kinda struggles with self harm) that I am REALLY proud that you've gone that long without it, and you should be proud of yourself! :)
In regards to what you should do, this is gonna sound cheesy but maybe you could write down what's bothering you, watch movies/tv shows you like, listen to music and have a good cry sesh (honestly, a good cry session does wonders), exercise, whatever you like to do. Just something that might make you feel like you don't have to.
One more thing: If for some reason you do end up self harming again, don't be upset with yourself, don't feel like a failure, and don't be mad at yourself for doing it. Because it's really fucking hard to deal with, and shit happens, people relapse, sooo you should still be proud of yourself, try your hardest to no do it, and if you do, don't feel like a failure b/c you're not and i'm proud of you and you should be proud of you too!