Don't lie about being not okay. If someone you trust asks you "How are you?", Tell them the truth. They could help you, Or find someone to help you. Don't hide behind a smile if you aren't okay. The smile can be a perfect mask for your emotions. I know that, I have hidden behind a smile many times. You don't want to worry your friends, I get that. You don't want to worry your family, I understand. But tell them anyway, They love and care about you. They want to help you. Don't lie, Lying once makes it easier the next time around. Even if you are bad at lying.
I have lied about being okay countless times. I hide behind a mask of a smile. It doesn't help to lie about it. If you think you might burden your friends, you probably won't if they are good friends. If you're scared to tell your parents, don't be, they will understand you, they might have gone through the same thing. Just try not to lie, please.