Few stories exposed the cruelty of Donald Trump’s zero tolerance immigration policies more than that of Estela Juarez. Just nine, she saw her mother, Alejandra, the wife of a decorated US marine, deported to Mexico, leaving her and her sister Pamela, then 16, to grow up in Florida on their own.

Now a teenager, Estela has written a book about her experiences, Until Someone Listens, which also chronicles her years-long effort to reunify her family.

From missed birthdays and holidays, the smell of Alejandra’s flautas no longer wafting from their kitchen, to Pamela’s high school graduation ceremony without her mother by her side, the story lays bare the pain of forced separation, even as the family never gives up hope of being whole again.

The book is not Estela’s first turn in the spotlight. Her fight included a heartbreaking video played at the 2020 Democratic convention. As images of migrant children in cages filled the screen, she read a letter telling Trump: “You tore our world apart.”

Now, with a colorful illustrated book aimed at children, albeit with a powerful plea for immigration reform directed at adults in positions of power, she is bringing her story to a new generation, with the message it is never too early to stand up for what’s right.

“I know that if I decided to never share my voice then my mother wouldn’t be here right now next to me, and she wouldn’t be in the US,” Estela said on a Zoom call from her home in central Florida.

“And I think that’s very important for other people to share their voice and I hope that they can get inspired by my story, and know that they’re not alone, because I know it’s hard to speak out, especially at such a young age.”

Alejandra was able to return to Florida in May 2021 after almost three years in exile in Yucatan, as one of the early beneficiaries of an executive order signed by Joe Biden in his first days in office.

The action reversed the Trump policy of deporting undocumented residents without impunity even if, as in Alejandra’s case, they’d lived in the US for decades, paid taxes, were married to US citizens, had US citizen children and stayed out of legal trouble.

Biden’s order also directed the Department of Homeland Security to form an interagency taskforce to identify and reunify families separated under Trump. An interim report in July revealed that 2,634 children have been reunified with parents, with more than 1,000 cases pending.

“We’re spending as much time as we have together and we try not to think about the fact that in a year or so my mom could be deported again,” Estela told me, referring to the temporary nature of her mother’s immigration “parole”, which will be reviewed in 2023.

“Knowing that my story is not finished yet has inspired me to continue to write another book that’s more for teenagers and adults, and to give them a chance to be inspired.

“I love writing, it helps me get my emotions out. When it comes to children’s books it has to be brief, and my story is very complicated, so I have to make it in a way where other children would understand.

“My mother was never supposed to come back from Mexico. She was told she would be there for life. And knowing that after almost three years of being there she was able to come back shows me basically that anything is possible, so I have a lot of hope for the future.”

Estela has grown since the Guardian first met her, Pamela and Alejandra in a playground in Haines City, Florida, in late summer 2018, about a week before their mother was deported.

But even then, having only just turned nine, an advanced awareness of her family’s plight and that of others sat comfortably alongside her joyous, playful nature. She spoke eloquently of immigration reform and working with a Florida congressman, Darren Soto, on a bill to protect military families if any member was undocumented.

Now 13, Estela is in her final year in middle school. She is studying the naturalization process in civics lessons she says are helping to inspire her career path.

“I hope to become an immigration lawyer,” she said. “I know that right now I’m a minor, and with my writing I’m doing all I can to help immigrants. In the future I want to continue to help them.

“Seeing how the broken immigration laws hurt my family, and others, seeing how it changed them forever, really gave me the courage to continue to speak out and spend my time helping them.”

As Estela says in the book: “My words have power. My voice has power. I won’t stop using my voice until someone listens.”

• Until Someone Listens: A Story About Borders, Family and One Girl’s Mission is published in the US by Macmillan