Kylie Jenner is ''very proud'' of what she's accomplished at a young age.

The Kylie Cosmetics mogul recently celebrated her 21st birthday, and after being named one of America's richest self-made women by Forbes magazine last month, sources say she can't believe how much she's managed to achieve before she's barely begun her 20s.

An insider said: ''[Kylie] is very proud that she is only 21 and has accomplished so much already.''

But the 'Life of Kylie' star believes that by far her biggest accomplishment has been her six-month-old daughter Stormi, whom she has with her boyfriend Travis Scott.

The source added: ''She says the best thing to happen to her is Stormi. She is crazy about her little girl. She gets a bit emotional thinking back about everything amazing that has happened this year.''

Kylie celebrated her birthday in style earlier this week, but hosted a smaller celebration at home with her tot for company.

The insider told People magazine: ''She had a smaller birthday celebration at home with Stormi. She just loves being her mom.''

The 'Keeping Up with the Kardashians' star kicked off her birthday celebrations with her family and friends - including mother Kris Jenner, and sisters Kim Kardashian West, Kourtney and Khloe Kardashian, and Kendall Jenner - with whom she enjoyed a dinner at Craig's in West Hollywood.

The group then headed off to nearby nightclub Delilah, which had been decked out with floral arrangements and a ball pit set up in the back room.

The party theme continued with the decor and there were ''Kylie F***ing Jenner'' lighters scattered everywhere. Guests could choose their cup colour depending on their relationship status - red for taken, yellow for single and green for it's complicated.

A source said: ''People were having fun choosing and were messing around. All of the girls were drinking together. Everyone was letting lose and having a great time. Even Kim was drinking and everyone was surprised.''

Also in attendance at the event was Kourtney's ex-boyfriend and family friend Scott Disick, Kris' partner Corey Gamble, Khloe's best friend Malika Haaq, and Kendall's boyfriend Ben Simmons, as well as stars including Chris Brown, Cara Delevingne, Bella Hadid, French Montana and The Weekend. Caitlyn Jenner also made an appearance.