Since I know how much it sucks if you're feeling down I wanted to share some tips with you on how to become happier.

Spend time with the right people:
Maybe you already found them or you still have to change something. If your ''friends'' make you feel bad then they are basically not good for you. I don't want to tell you that you have to leave them behind right away. Maybe just talk to them and tell them how you feel can help. If it doesn't honestly these people aren't real friends.
And keep in mind that there is also your family who should be there for you, too. Here the same, if something doesn't feel right to you, talk to them.

Talking to people in general:
Not only if there is a problem withing a relationship but also if you have problems in general you really should talk to someone you trust. Just acting like everything is fine but feeling worse with everyday doesn't help at all.
If it all feels senseless to you remember that there are experts who can help you. (Just for the worst case)

Be yourself:
I get why people act different with different people. It is natural to want others to like you. But acting like being someone else is only depressing. You always have in your mind that these people don't like the real you and that makes sad not happy. Also it is exhausting and simply a big lie you are living in.

Find your Passion:
It can be any kind of sports, art, music or any other thing. Find out what you love, probably you already did so and if that is the case then just do it. Doing what you love is so important to feel good.

Don't do what you don't want:
The contrary the the point before. Yes there are things you just have to do like going to school or working. But you should never do something where you have the choice just to make others like you and things like that. If you really don't want it don't do it. That won't make you feel better I mean how should it?

Go outside:
Fresh air always makes me feel better and nature is such a beautiful thing. But also the sun gives you important Vitamin D which makes you feel better.
Of course you can combine going outside with spending time with the right people. Win win.

Take time for yourself:
It is important to spend time with others but also to take time for yourself. You can just have a comfy day in bed or do whatever you enjoy. You should do what makes you feel good and somethings to reach that you just have to be alone so don't aim to never being alone for being happy.That won't work trust me.

Bananas:
Sounds weird but bananas are said to boost the production of happy Hormones so if you like bananas anyways feel free to eat them in nice amounts.