How to make myself feel sexy

My whole life I've always been a second choice. I've never been confident in my self at all. I've delt and am dealing with depression and am taking medicine (occasionally) for it. I've tried a lot of things to help me but none works. I've tried different hobbies but I seem to be good at nothing. I am currently dating a guy and we'll make a year in December. I feel as if he thinks I'm not good looking enough, where I live there is so many gorgeous women with AMAZING body! And here's me a 17 year old with a gut and no ass. I just don't want him to see me the way I see myself. I don't want to depend on other people to make me feel better. I want to learn how to love myself and feel sexy in my own body! I'm a very boring person, I love staying at home and reading. I don't have much friends, my boyfriend loves drinking and partying but also knows when to stop. But when we do go out I'm always bored. We're totally different people but I love him. I feel as if even our sex bores him. Idk I just wish I was happy and confident in my own body! How do you do it? How can I make myself feel and be beautiful and confident. I'm a thin thread :(