Kardashian has gotten plenty of practice taking care of her nieces and nephews, and now she reportedly "really wants a baby," claims the source, and "she hopes it will happen soon."
Kardashian and Thompson, a 26-year-old NBA player for the Cleveland Cavaliers, have been dating since Fall 2016.
"She is absolutely hoping for an engagement," the source said, adding that Kardashian "is very happy and positive about her future" with Thompson.
The lovebirds have seemingly been inseparable ever since becoming romantically involved last year, with Kardashian often traveling to Cleveland for her man's basketball games.
On the season finale of Keeping Up with the Kardashians earlier this month, Kardashian visited with a fertility specialist and was informed she should have no problem getting pregnant in the future.
The reality TV star and Revenge Body host also revealed during the episode she had decided to stop taking birth control.
"He wants to have kids now... Tristan and I definitely talk about starting a family," Kardashian said in a confessional on the show. "He wants to have about five or six kids with me and that's lovely. We could start at one and we could grow from there. It's scary. It's a really big step."
Thompson is already dad to six-month-old son Prince, whom he welcomed with his ex-girlfriend Jordan Craig in December.
"Khloe has spent some time with his baby," the source told People. "She is very attracted to Tristan as a dad, too."