Kim Kardashian is reportedly feeling like the odd one out after her two sisters are getting married and planning babies.

The 28-year-old is dating NFL star Reggie Bush, but her younger sister Khloe, 25, recently married boyfriend Lamar Odom and sister Kourtney, 30, is expecting a baby at Christmas.

A source said to FOX411: “Kim didn’t expect to be the last of the three Kardashian sisters married and having kids.

“Khloe will be travelling with Lamar and eventually wants to have babies with him while Kourtney and Scott are talking about a wedding next year after the baby… there’s actually a lot of competition between the sisters and Kim had a moment where she felt like the lame single one who was too focused on her work.”

Kourtney and boyfriend Scott Disick, 26, are expecting their first child, a boy, in December and insiders say she is already a “little mother”.

The insider added: “Kim is nothing but excited for Kourtney’s new baby and is turning into a little mother already.

“She is practising with every child that comes her way and gets down in public and picks up and plays with strangers’ children. Kim is excited about the birth and plans on being in the delivery room with Kourtney.

“Kim, Kourtney and Khloe were always competitive as children and now Kourtney and Khloe can finally compete evenly with Kim in adulthood.

“In years past, Kourtney and Khloe felt like second string sometimes, but they are rising to the top on their own power now. The three of them will always fight and yell and then make up.”