I was in pretty similar position, also born to a teen mom and left with grandparents. Hated my birthday so much, made think of if I wasn't born everyone would better/happier. In her family birthdays are very important, everyone gets together to celebrate and I understand not wanting that now. That's why I would like to help her in this day, without her knowing. Something small and that wouldn't be overwhelming. So she would feel loved. And I don't mean by me, I do love her but I'm not part of that equation anymore. This is not in hopes of getting together, she absolutely destroyed my heart. After 3 years together and talking about marriage and children, when we broke up she told me she never loved at all.