Before Feb. 14, Emma Gonzalez was like any high school senior: hanging out with friends, visiting college campuses and counting down the days to graduation.

But when a former student stormed into Marjory Stoneman Douglas High School in Parkland, Fla., and fatally shot 17 people, her life changed. In the aftermath of the tragedy, she has become a national voice on the movement to reform gun laws.

“Now we don’t really know if we’re going to go back to school,” Gonzalez, 18, told PEOPLE. “After this is over, that’s what we want to do, but I don’t control the school board. I don’t make the decisions.”

Gonzalez garnered national attention when her anti-gun speech on Saturday went viral, instantly making her “Twitter-famous” and placing her at the center of the conversation on the issue.

On the day of her speech, she said, she woke up early and chose every word carefully. She edited it until the moment she walked up to the podium and shared her grief, catching the attention of several celebrities – including Zandaya, Laverne Cox and others.

“I was trending on Twitter,” she tells PEOPLE. “I didn’t even have a Twitter account! I had to go make one.”

News: Parkland School Shooting
Emma Gonzalez
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She remains in shock over the support she has received. Only four days prior, she was living the life of a normal soon-to-be graduate by taking a tour of New College of Florida, a liberal arts school in Sarasota.

“There was literally an Emma on campus giving tours,” she says about the campus she loved. “I was like, ‘You’re a senior. I’m a senior. One Emma leaves and another Emma enters.'”

Still, she hasn’t completely made a decision about college. She was moments away from accepting admission to New College when she received an email from Drew University in Madison, N.J. – another school she toured – stating they wanted her on campus after seeing her speech.

Gonzalez has many things to think about, including her major. She was leaning toward studying environmental studies and becoming an activist and hoping to work at NASA, but after last Wednesday’s tragedy, she is reevaluating everything.

“There has been such a dramatic shakeup in my life,” Gonzales says. “I need to see what I can add to the human race, at this point.”

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For now, she is focused on the March 24 “March for Our Lives,” a national march in Washington, D.C., as well as across the country, aimed at reducing the epidemic of mass shootings.

After speaking with state legislators with fellow classmates in Tallahassee today, Gonzalez and her peers will be speaking at CNN’s Town Hall meeting at 9 p.m. Wednesday night.

The public has been impressed with Gonzalez, whose father is an attorney and whose mother is a math tutor, as she remains focused on her advocacy for mental health reform, gun safety reform and working to defeat politicians supported by the NRA.

“This is the worst thing that has ever happened to us,” she says about last week’s tragedy. “We’re taking care of business the only way that we know how.”