You can try read some self help and motivation book. Do some exercise and take bananas. I heard that bananas are good for depression. Talking to a professional person in the related field is sure a big help. I hope that you'l be able to get all the help that you need . Life is precious do not hurt or harm yourself in anyway. I know its not easy but I think and feel that you should always give life a chance. The more you feel like dying the more you should fight and live. Think of your purpose in life. Think of your family and loves one. Ask yourself have you live to the fullest yet? Have you fufilled your dreams ? Have you tried and experienced everything that life have got to offer you? Have you make a difference yet ? Most important will you regret ? Think over again about everything. You have come this far so that gives you even more reason not to give up easily. Its important to accept and love yourself even more. Be kind to yourself . Think positive and have faith. Seek comfort and guidance from God. Believe in yourself and believe more in your dreams.

Well, the best way to not think about suicide is talking to a professional who can help you with whatever you're going through.
And yes, it's cliché as and also annoying as (I can't even count how many times I wanted to punch people who said "talk about!!!" in the face in the past) but it genuinely works to just have someone.
Since your parents are obviously not Good Parents that take you seriously you need someone else. And someone you can trust. Some uses a teacher, an adult friend - you know what? I don't really care /who/ you talk to as long as you talk to /someone/.
You can also call a suicide hotline or - if you're sociophobic like me - find a suicide hotline chat (I'm positive they are in your country as well). If anything you can find online help-sites. They're good.

Now - if you selfharm, the best way to conquer that is to take small steps and try to replace the habit of selfharm with something less harming. It could be painting, writing, drawing, singing, punching a pillow, screaming in the night, poetry, reading, gardening - whatever man. It could be anything as long as it doesn't inflict you pain but instead makes you feel absorbed in it. It's not supposed to remove all your problems, it's supposed to give you a safe space. Safe spaces are important. When you find them, remember them and use them for practically /anything/ that distresses you or when life gets rough. (Because it does again because life is just that cruel).

You are STRONG for living through 2 years of this already. That's strength, ok? Remember that. You're living. Living is strength. I'm proud of you for living. I am.
And it's okay to have fall-backs, we all do. Small steps. Nothing disappears overnight. (And if it's done, it's not really gone and it will come attack you again.)

I really don't know how to help tho but i've been there and i know how you feel.
First at some parts of my life i really grabbed a bottle of sleeping pills and thought about swallowing it all.
The result i'm still here :) and you know it's not because of anyones help because no one tried to help me or payed attention to my struggle BUT because i deserved another chance
So for my advice, i really really hope you believe in another chance, you're young, no matter how troubles you're in now, it's temporary, you can do it.
Love life, find something you like, sports for example; it help busy your mind and relieve stress, and don't give up. Take a long walks and try to see beauty in everything you see, i hope you tell someone you trust, a friend or someone who can help you by being there for you
I'm here for you, if you want to talk, i hope you smile more and forget about everything that upset you

I really hope your thoughts will go away that makes you take action. Remember, if you take the life, you'll never see your mother again. Not your mother, father, other family members, and friends.
What I do to not let negative take over my brain, I just write my worries out. Either if it's for my stories, a person letter, etc. It can also be for listening to music you like, or watching movies/dramas, variety/reality shows, etc. If you find out your way to relieve your stress, that's good. do what you love the most, and you'll realise it helps you a lot and distracts your thoughts.
I hope you'll get better and not think such thoughts like taking your life. You'd never see anyone again, and you won't only hurt yourself, but also the people around you who loves and cares for you. Taking your own life means either you weren't strong enough to keep going, it that it was the absolutely last resolution to what you could've done.