Adolescence is a rough time for many people and it doesn't make it any easier when there is something, such as weight, which makes you stick out. First, it is important to make sure that your daughter is not actually suffering from depression
. I would recommend making an appointment with your primary care provider to screen her for mental health issues. During this visit it is also important to address her weight and make sure she is living a healthy lifestyle. Secondly, it is to make sure she is not being bullied or feels unsafe in any way at school.
Self esteem is important to being a happy well balanced individual and I commend your efforts to help build your daughter's confidence. Showing your daughter unconditional love, as you are doing, is the most important thing you can do. Encourage your daughter to pursue activities in which she is able to show off her talents. Make sure she is getting enough sleep and exercise. If your daughter is upset by the taunting, it can be very helpful to talk to a counselor or psychologist
to help her with coping strategies and realizing her inner beauty.