Be who you want to be. Never let yourself be diverted from the path you want to take. Don’t let other people create the path for you. For example, if your parents want you to be a doctor but you want to be a musician, be a fucking musician.
Indeed. You are never going to be happy if you try to live your life for someone else. Live for yourself first. Do what makes you happy. And hopefully, those you love and who love you will see your happiness and feel it with you. Regardless of what they want(ed) for you.
Be yourself. It’s the only person you know how to be naturally.
No one should be the substitute for anyone. Every person is worthy of their own place in the world.