The friendly exes celebrated their son's fourth birthday with a party fit for a superhero over the weekend.
Speaking to the guests who had come to celebrate - including Lamar Odom and Blac Chyna - Amber said: "We love Sebastian. He's our beautiful child. He's super awesome. Happy birthday pumpkin."
Meanwhile, the 30-year-old model previously admitted she has "a million different fears" as a mother.
She explained: "As a mom, you have a million different fears. You don't sleep at night. You think about all the worst things that could possibly happen to your baby, and it really sucks. I literally almost shed a tear every single time when he hugs me really tight and he says, 'Oh, Mommy, I love you so much.' I want him to do any and every thing that makes him smile and be happy forever.
"I read to Sebastian every single day when he was in my arms, and now he can articulate a sentence like no other, and he's three-years-old. He knows every big word. And every time your baby says something like, 'Oh, this is relaxing,' you be like a thesaurus and you give [them] a different way to say it every single time so they learn.
"I gave him a piece of strawberry gum, and he was so dramatic when I gave it to him because he said, 'Oooh, Mommy, this gum feels so therapeutic.' And I just laughed on the floor until I cried."
And Amber also doesn't want any mothers-to-be to be too worried about becoming a mother as it's easy to just "figure things out along the way".
She told PEOPLE magazine: "I read every single book, when I was pregnant, about being a mom and being pregnant and doing the right thing, and then I had my baby and I was just like, 'What the hell do I do now?' Your maternal instinct comes in, and you figure it out along the way. And that's the fun part about it."