correct me if I'm wrong but she's isekaid right? she's not the real daughter right?

No she is the real daughter she just remembered her past life in her life as juvel. She did say that she regained her past memories 2 years into her relationship with that blonde guy. She also says that her attitude before was true to the novel its in chapter 2

but look at the summary, i also remembered that she told the story of past jubelian and how she reincarnated to be her (present)