She must enhance her bust!

Us Weekly has learned that Teen Mom 2's Jenelle Evans is going under the knife for a breast augmentation -- news that E! News reported first on Wednesday.

"She's wanted it for a long time," a source close to Evans tells Us about the 20-year-old's plans for a boob job. "She's been to a consultation and is bragging to everyone that she's going to get them done."

"She just doesn't want to be as small up there anymore, I guess. Gary is kind of egging her on to do it, too," the source adds, referring to Evans' marine boyfriend Gary Head.

Evans follows in the footsteps of Teen Mom's Farrah Abraham, who went from an A to a C cup in early 2011.

"I thought I lost 'boobage' from having a baby," Abraham told Us during a visit to our New York City offices in June. "It was a challenging time, [but] it's helped my confidence and [made me] feel more like a woman."