The 35-year-old also said she is "proud" of her journey" but revealed to fans that she is "sad" she will never be pregnant again.
"But I'm proud of where this entire journey took my body and mind in other ways. I love being pregnant, so so much, and I'm sad I never will be again," she wrote.
"But I am lucky to have two amazing little ones who are transforming into big little people more and more every single day. Anyhoo. Love u guys."
Teigen received thousands of supportive comments to her post, and was praised for candidly sharing her tragic journey.
The model and her husband, singer John Legend, shared their heartbreak with the world when they lost Jack in October, and have kept fans up to date since then.
"You have helped so many people sharing your story!! Love you," one commenter wrote.
Numerous people took to the comment section to let Teigen know her posts are helping others.
"Love you, am heartbroken you're going through this - but am so thankful that you're sharing with the world. You're helping a LOT of people, and we've got your back,' someone else said.
"I see love, strength, boundless beauty and a story that is all your own yet one that so many can relate to as well. You are such strong woman and you sharing the trials and tribulations of your life has given many comfort in knowing that no life is 'perfect' but if we can keep the faith, we can take steps every day to get through the tough times," another one said.