I agree that it would be wise to get your weight under control. If not to be attractive to girls, it would help your general health and longevity. Seeing a nutritionist is essential and start getting more exercise.
Truth be told, I think a lot of teens are shallow about looks. Some grow out of it as they mature and some will always be shallow -even as adults. So, yeah - this makes it tough. And double this with your shyness about approaching girls and it's going to be tough for you.
Question for you: what do you think would boost your self esteem?
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.