Princeton University and the University of Pennsylvania were "reaches" for Angelyn Ansah when she started applying to colleges in the fall, she says.

"I applied to those schools just to apply [and] see my chances and to see how everything went," the 17-year-old from New Jersey tells CNBC Make It.

She got the shock of a lifetime when acceptance letters came from both Ivy League institutions on March 28 — what's known as "Ivy Day," when the elite colleges announce their decisions to hopeful seniors. 

Upon opening her letter from Princeton, "I was like, 'Woah!' I did not expect that at all," Ansah says. "Then the minute I opened Penn — right after, and I got in — tears started flowing because I was just super happy and surprised, but it was a really good moment."

After relishing the shock and accomplishment of getting admitted to both highly competitive institutions, Ansah had a big decision to make: Where would she call home for the next four years?

It can be a difficult decision for a 17-year-old at any point, especially in recent years. But Ansah also didn't have all the data she needed to make an informed decision right away — mainly, what the actual cost of attendance at each school would be.

Here's how she decided where she's heading in the fall.

Facing unknown costs of attendance

Ansah knew she needed financial aid to attend college.

"I didn't want to go into debt because I know a lot of people acquire a lot of [student] debt and they have to pay back a lot of money after college," she says. "I knew that ultimately the decision of where I'm going to go would be heavily impacted by the financial aid aspect."

Typically, when incoming students receive their college acceptance letters, they also receive a financial aid offer if they applied and qualify for assistance. This year was not a typical year. 

Students and families must submit the Free Application for Federal Student Aid to be considered for federal aid, as well as many institution-based grants and assistance. An updated version of the FAFSA launched this year, but numerous technical issues delayed the entire process.

Students and families struggled just to access the form for over a month after it first opened in late December. And now, as students are making college decisions, some still haven't seen financial aid offers.

"It's been a challenging year and this hasn't gone the way we planned or we wanted it to and that has caused some confusion [and] anxiety for students and families," a senior Department of Education official tells CNBC Make It.

"That said, the FAFSA is up and running. We've received over 9 million applications, and people that come to the FAFSA today will see their application process and sent to schools within one to three days."

Ansah was able to submit her FAFSA pretty seamlessly, she says. But neither of her acceptance letters from Penn or Princeton included financial aid award information. Ansah knew her parents wouldn't be able to pay either Penn's $60,920 or Princeton's $62,400 tuition fees out of pocket.

Penn and Princeton weren't her only options. She'd been accepted to Rutgers University, where she'd qualify for discounted in-state tuition even before financial aid came into play, as well as Howard University and the University of Maryland.

Getting accepted to two Ivy League schools helped narrow her choices though, expecting that the prestige and global recognition of schools like Penn and Princeton could take her far. 

"Knowing that I can attend a university or college…that ultimately just the name on my degree or on my resume can give me so many opportunities, that was a big factor in me choosing the school to go to," Ansah says.

'Show me a sign'

With her options whittled down to Princeton and Penn, the waiting began. Ansah loved both schools and would have been happy committing to either one, she says. But she continued to wait to hear about financial aid and prayed about her decision.

"'Wherever I'm meant to go, let God show me a sign,'" she says she told herself. Soon after, a financial aid offer from Princeton arrived. It didn't quite seal the deal, but Ansah took the fact that it came in first as a sign.

Princeton sent Ansah an institutional award package in early April with enough grant funding to cover her costs. Later, the school received her FAFSA information and adjusted her aid offer accordingly to include federal assistance.

All considered, Princeton offered her a grant of $79,643, which, along with a $7,395 federal Pell Grant, would cover the entirety of her cost of attendance for her first year — including the $62,400 tuition and just over $24,000 in food, housing and supplies costs.

Ansah wanted to wait and see what Penn may offer before she made her final decision. But both Penn and Princeton maintained the May 1 deadline for incoming students to commit, so she couldn't wait forever.

A February blog post from Penn says the school would send financial aid offers with admissions decisions for students who submitted all appropriate paperwork. Penn notified Ansah in March she was missing a document, which she then submitted. However, her financial aid package from Penn didn't come before May 1.

If Penn was her top choice, Ansah could have asked for an extension on the commitment deadline. "Penn is committed to working with admitted students on an individual basis in the event they need an extension to our enrollment deadline," a spokesperson for the university wrote in an email to CNBC Make It.

But Ansah had already made up her mind.

"The FAFSA delays had such a big impact because if I did get the package from [Penn] earlier, that could have changed my decision," she says. "At the end of the day, I love Princeton, and I'm really glad to be committing there."

A similar or better financial aid offer from another school may not have necessarily swayed her decision, Ansah says, but it would have made it more difficult.

For future college applicants, Ansah's best advice is to "be patient."

"That was the one thing that got me through this because it's a long [process]," she says. "In order to get through, you have to have patience, remember that things will come in time and to just trust that everything will work out."

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