Ashley Ness, who previously struggled with infertility, is celebrating a medical miracle after she and her boyfriend welcomed two sets of identical twins simultaneously.

The quadruplets and 35-year-old mom are doing great. "I feel amazing!" Ness told PEOPLE.

Ness and her boyfriend welcomed all four babies — two girls and two boys — via C-section at Massachusetts General Hospital in Boston. A spokesperson for the hospital said that "everyone is doing well so far and recovering."

The babies made their grand entrance into the world 12 weeks earlier than expected. Dr. Ahmet Baschat called Ness' "high-risk pregnancy" pregnancy a 1-in-10 million rarity, telling PEOPLE, "If she were playing the lottery, she would be very rich."

Dr. Baschat explained that two twin pregnancies occur when two eggs are fertilized simultaneously, and each fertilized egg divides, unlike traditional quadruplets, where each fetus represents an individually fertilized, separately encased egg.

"We see a lot of rare stuff, but this is the first time I'm hearing this in my entire career," the doctor told PEOPLE.

Dr. Baschat wasn't the only medical professional who was perplexed by the pregnancy. Ness' ultrasound technician, who discovered Ness was pregnant, "had to step out of the room to Google it to make sure."

Before welcoming the two sets of twins, Ness was already a mom to 8-year-old daughter, Chanel. Her boyfriend, Val, already had three children as well: Zayden, 7; Isaiah, 10; and another son, 24.

Adding more children to her family was the last thing Ness expected when she went for a routine gynecologist visit back in February.

Ness, who previously experienced four miscarriages, "just kind of accepted that I was blessed with one child, and I took on his boys as my own." The news of her pregnancy was a big, happy shock.

"It's truly been just a blessing after a blessing," Ness told PEOPLE. "Even so, I was like, oh man, I'm going to mix them up. I'm going to forget who's who. They're going to play tricks on me. This is going to be crazy."

Ness, a part-time hairstylist, and her boyfriend, a mechanic, share a three-bedroom house in Massachusetts. They recently launched a GoFundMe to help raise funds to cover the unexpected financial strain of expanding their family by four.

"The average cost to raise one child is [$17,000] per year," the couple wrote on their GoFundMe page, which has so far raised more than $22,000.

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