Author's note
I am sorry if I didn't explain myself enough for the last chapter. So, here's what I meant.
The two Emmas share the same soul. The teenage Emma dies to allow her mother to live. Then, she wake up eight years later as a child. The eight years that she lost(her memory) were the price she had to pay for time-travelling. However, she has the chance to grow up with her family, even if she has to start from scratch.
I hope my explanation helps you