You know, I think people are not giving Bella enough credit. The lack of self-worth for both her and Edward is something I only see when they're thinking about the other person. They both view each other on a different plane of existence. Bella sees Edward as out of reach because he's insanely beautiful and mysterious and unique, etc. Edward sees Bella as out of reach because she's human and deserves to live a life that isn't plagued by his monstrous existence.
But both of them had lives before the other and both of them still maintain connections to people outside of their relationship with each other. I find nothing wrong with a person choosing to connect themselves with others and serve others in a genuinely altruistic manner. But it's not even really that. Bella love Charlie and enjoys cooking for him and being what to her certainly feels like the woman of the house. She likes the independence that comes with living with Charlie; it's very much, to me, an adult-like thing. It feels similar to me, when reading her reaction to living with him, to the way I felt when I finally got an apartment with my husband. It was oddly liberating feeling like I had a place of my own and "grown-up" responsibilities. She has interests in music and books the same as anyone, she likes cooking and keeping a tidy home. She had an existence before Edward; she wasn't void of all purpose. And she doesn't completely abandon that after either. The same goes for Edward. He had a place in his family, which one could claim was his reason for living. If you're going to claim that all Bella lives for is other people, then you can make that argument for tons of people. Hell, life is about the connections we have with other people. Some people are perfectly happy to define themselves based off the people they keep around and love in their lives. I think people have become too selfish and forget that, not too long ago, life was solely about being a place holder in a smaller community, serving a specific purpose to the people around you. Think of people who live in tribes. Their lives are to make sure that everyone gets what they need, not to serve their own selfish desires.
Yes, individuality counts for something, but I think Bella has plenty of that. She certainly has her own opinions, and that is the most important part of an individual, in my opinion.
Precisely because death awaits us in the end, we must live fully.
Stars did fly toward each other, irresistibly, as if they were falling in love. And millions of years later, lovers on Earth drew together and fell in love, watching the stars fall.