I've had to struggle with body image since I was a child - it's an on-going battle that can be won. Improving your self-esteem may be difficult, but not impossible.
Suggestions:
1 - Part 1) Stay away from cosmetic surgery if at all possible.
I have been aiming towards having plastic surgery since I was 13 or so and have already consulted with cosmetic surgeons. If you do further research, there are all sorts of disaster/ unhappy stories - even with the best doctors. You will see many patients stating: "Had I known I would have ended up like this, I would have been happy with what I had." With so many factors involved in cosmetic surgery, you're essentially gambling with your face/ body.
1 - Part 2) Body Dysmorphic Disorder/ Unrealistic Expectations
I am not diagnosing you, but this might be something to look into. These are two threads I posted a while ago with articles and videos of people with BDD:
http://www.alonelylife.com/showthread.php?tid=10117&pid=174528&highlight=body+dys#pid174528
http://www.alonelylife.com/showthread.php?tid=10118&highlight=body+dys
For a while, I felt that I was looking back at a monster every time I looked in the mirror. My low self-esteem impaired my ability to "be seen" in public places etc. I find that learning of other people's situations helps me find perspective in mine. Perhaps it may help you too.
2) Healthier habits.
What helped my self-esteem the most was getting into shape by exercise and eating well. I'm not suggesting that you need to lose weight, but rather that it helps to be more active.
Eat better and you'll feel a lot more productive and cleaner.
To help keep me motivated, I joined a weight loss forum, looked at people's before and after photos, kept a food diary and I was able to lose approximately 15+ pounds in two months and have kept it off for 4 years.
3) Grooming
Learning to take better care of my hair (don't heat/ straighten it to death) and also learning to apply simple make-up has helped me in building a positive body-image and self-esteem. It's important though that you do not wear it as a mask or become dependent on it. It's moreso to help you enhance your features. Don't say that there's nothing good for you to enhance - you might be surprised if you just look a little closer.
4) Hobbies/ Career
Make sure to also invest your time in your interests and talents. I have met people who are very fit etc, and all they do is worry and work on their appearance. It's very off-putting and not healthy.
5) Reach out to People
For some people, having a family member, friend, counselor etc to talk to helps. For me, I reached out to the people here and it has helped me learn a lot about myself.
FINAL) I'm sure that there is a lot more you can do to help you feel better about yourself. This is all I can think of that the moment, but if you have any questions or would like to talk, you can post here or PM me. I hope this helps. You gotta try...doing nothing helps no one. I learnt that the hard way.