Pretty- First,
I think everyone struggles with those feelings, regardless of how "accomplished" or not they are. By most standards, I am a very accomplished young woman, and yet I still feel a crushing amount of pressure not to let my parents down, and to live up to their standards...and they are supportive for parents! Well, not about my weight, and maybe I project that disappointment onto other areas of my life as well.
Cliche as it is, true happiness comes from within. To paraphrase Michelle Obama, don't look at the money or the looks or even the job title--all those things can fade, and you're left with who that person really is at their core. That has to do with your core beliefs and values, like aspiring to be a good mom and to better yourself. Becoming a mother at a young age doesn't define who you are--I think it's the other way around: who you are as a person defines how you'll rise to the challenge of becoming a young mother, and it sounds like you're proud of how you've done by your child. It's virtually impossible these days to have the "American Dream" on one income, and we as 20-somethings are adapting--many more of us get support from our parents for longer, and that is nothing to be ashamed of. No one makes it through life alone, we all receive support from various places (parents, luck, birth, public assistance, friends, etc) at some time or another, it's just part of the human condition.