It doesn't matter love the person you are, both the inside you and the outside you. Walk around knowing you look good be caught up on the outside will drag down the inside you. Your not fat and don't put yourself in that category.
If you're fat you'll know it. It doesn't matter whether other people think it's fat. You don't need their opinions on beauty which is so subjective anyway to validate who you are! the real question is, do you think it's fat? If you do then that's your issue that you need to resolve in your own way whether its physically or psychologically. If you don't, then great! If you're happy then why do you need to doubt yourself?