Her shirt reads "Keep moving forward." But now that defiant message is a reference to her attitude more than her aborted journey to the United States.
"Let's live in the present moment," she said in Spanish, smiling shyly. "To be sad? No. To think about things I've left behind? No."
Amarilis' father, Rocael, decided the trek north was just too dangerous -- and given what they've heard about President Donald Trump's immigration policy, they no longer see the United States as the promised land. They are among a growing number of migrants from Central America who are choosing to stay in Mexico, either temporarily or permanently. Mexico's Department of the Interior reports a 150% increase in asylum applications since Trump was elected.
Instead of continuing the journey to the United States, the Mendozas have found a new home at the Jesus El Buen Pastor migrant shelter in Tapalucha.
"When we left we heard nothing about the President," Amarilis said.
"Now we heard they were deporting everyone."
People 'forgot about the American dream'
"After the new President in the United States, many people forgot about the American dream," said Angel Morge of Tapachula's Office for Migrants and Refugees.
"They don't want to go up there because they know they're going to have problems."
According to Mexican Foreign Minister Luis Videgaray, the number of people crossing Mexico's southern border is trending down.
"We don't know yet if this is a long-term trend," Videgaray said.
But the Trump administration claims this as a victory.
"Border security for the United States starts 1,500 miles to the south (in Central America)," said Department of Homeland Security Secretary John Kelly.
"Thanks to President Donald Trump," Vice President Mike Pence said, "illegal crossings at America's southern border are down nearly 70% since the start of this year."
Not everyone here sees Trump's stance on immigration as lasting policy. Along Mexico's southern border with Guatemala, it's not hard to find people who are biding their time, waiting for politics to simmer down.
Journey begins with river crossing
For many of the more than 75,000 Central Americans who US Customs and Border Protection officials say have been apprehended at the US southern border since October, the journey north began with a crossing of the Suchiate River.
Under a sweltering sun and cloying humidity in Tapachula, the river marks the point where Mexico and Guatemala meet. "Right here they don't have any restrictions," said Jose Delgado Espinoza, as he stepped off a raft onto Mexican soil.
He lives in Guatemala and crosses the river often to shop and visit friends. Carrying a backpack and wearing a cap and Air Jordan T-shirt, the 28-year old said he returns to Guatemala at the end of his day.
But soon, he hopes, he'll cross the Suchiate and never go back, continuing north to the United States, where he lived as recently as last year.
"(Trump) is not stopping me because I want to be with my family," he said.
For a mere 25 pesos, about $1.25, anyone can cross the muddy water between Mexico and Guatemala. The border has a flea-market atmosphere, with a constant exchange of goods and people. Families, elders and infants hold onto each other as they cross the river on surprisingly sturdy wooden rafts, some looking more like floating shopping carts, as Guatemalans take advantage of cheaper prices in Mexico.
"Nobody stops them from coming into this country," said Morge, the Tapachula migrant official, pointing to how openly people make the crossing.
For Delgado, who hopes to reunite with family in Florida, crossing this river is the least of his worries. Fewer migrants means higher prices demanded by coyotes, or people smugglers, who claim to promise safe passage through the cartel-infested territory on the way to the US border.
Some migrants told CNN the price has doubled to $7,000 since Trump was elected
But coyotes and cartels aren't the only threat; the journey itself can be dangerous, especially for those riding a train known as The Beast.
A freight train called The Beast
Three hours north of the Mexico-Guatemala border, the once bustling town of Arriaga, whose economy depended in part on immigration, is a different scene today. Vendors once sold food, cellphones, and cardboard "beds" to immigrants.
The town is home to a station that's a stopping point for a freight train known to be a vessel for immigration north, called La Bestia, The Beast. Many migrants have been killed or, like Amarilis Mendoza, badly injured falling from freight trains.
Months ago, hundreds could be seen riding on top of the train, but that's not the case today.
La Bestia has seen a significant decrease in the amount of immigrants on the train. Standing near the tracks begging for money, Jose Marchado, is one of few waiting for the train's arrival.
"I got to get to the United States," Marchado said.
The Honduran said he has been deported four to five times from the United States. Now, he is determined to get back to Tennessee, where he once lived, and where his 2-month-old daughter, Angie, is waiting to meet him.
'I'm going to see my family'
Along with the rising prices demanded by smugglers and the activities of the cartels, Mexican police are also stepping up patrols.
In 2014, Mexican President Enrique Peña Nieto implemented the program Frontera Sur, or Southern Border. The program called for more patrols at train stations, cracking down on the flow of immigrants from Central America and forcing smugglers to find new routes.
Marchado knows the odds are against him, and even if he makes it to the US border he knows the challenge would just be beginning.
He's heard President Trump's tough talk; he's aware of the US crackdown on illegal immigration, but he only has one thought as he pulls up a photo of his daughter on a borrowed iPhone.
"They can lock me up, but I'm going to see my family."