Selena Gomez sparks plastic surgery rumours with busty Insta-snaps

In her latest Instagram photos Selena Gomez is looking much bustier than usual, with sources saying Justin Bieber is to blame for her allegedly going under the knife.

"She's studied every girl that he hooked up with while they were broken up," a source previously told Hollywood Life. "At least the ones she knows about. [Selena] compared herself to them down to every last detail.

"She's been asking people if they think she should get her boobs done because all the girls he was with have bigger boobs than her."

Well, Justin has been spotted a lot with busty 21-year-old model Chantel Jeffries…

But that's not all. Sources now say Selena, 21, wants to work on her booty too!

"She's been talking about it for months so it's not a surprise," the source told Hollywood life. "But she's not done, she's not happy with her booty!

"For God knows what reason, Selena has really low self-esteem. She has a long list of things she thinks she could improve as far as her appearance.

"Selena is putting a huge amount of pressure on herself to be sexy because she's afraid of losing Justin. She feels like she needs to be the hottest girl in the world to keep his attention."

But what's more worrying is that the Disney star also seems to have been partying pretty hard recently, besides the fact that she spent a few weeks in rehab earlier this year.

Selena and Justin were allegedly caught "doing lines" of cocaine in "dark, fuzzy" footage at Los Angeles nightclub 1Oak last month.

"They have been partying nonstop," a source told In Touch. "They clearly aren't worried about their behaviour."

Justin's sights seems to have shifted toward another model of late too, with no sign he's getting back with Selena any time soon.

Just yesterday the 20-year-old was posting up snaps with 18-year-old model Yovanna Ventura…

View slideshow: Next child star gone wrong? Tell-tale signs all is not well with Selena Gomez