Depression

I really need help my depression has been gettin to me for years, I'm almost 18 . I use to get bullied, I've had a horrible child hood and it's kinda interfering with my fiancé I have been with for 3 years.

I hate being sad and always over thinking. I also use to hurt myself I quit when I met my fiancé he helped me. And no I don't take any medication. I'm also insecure about myself. I jus want to feel good and be happy. What are things I can do to not feel like this.? Or any medication to help¿