It can take time to shake off the effects of early negative experiences, but I am encouraged that your recent years have been so much more appropriate to your needs. What you describe as cognitive dissonance can also be conceptualized as corrective reality testing, as more accurate feedback from your environment gradually affirms your identity as a capable and resilient individual. As more positive years become part of your personal history, the new healthy narrative will become increasingly the arc of your life story, while the bitter years will fade into a kind of prologue, possibly even one that can help you to become a more compassionate person, who understands, as you note, that even individuals who appear to have every advantage (whether in SES, education, physical strength or beauty, etc.) may bear invisible burdens.
I believe in your ability to become a stronger, kinder, and more creative person than anyone who may have misperceived you in the past could have imagined.
