McCain, 34, shared an inside look into the strong bond and special relationship the father-daughter duo shared for years before his death earlier this year.
She added that there is nothing she wants more than to have one of those mornings with her father now and that "I don’t know how you go from talking to someone seven times a day to never."
The grieving daughter compared life now to some kind of "parallel universe I fell into."
"The pain of missing you and the grief that comes with it continues to be sharp and primal. Some waves are more intense than others but they come every day relentlessly," she added.
But as she's said before, her father made Meghan strong and instilled his resilience into his beloved daughter.
"I fight on because that is what you told me I had to do and demanded of me. I know you made me so tough and strong with the intensity that only you could have purposefully - and for that I am the most grateful," she continued. "I love you forever."
She closed with a note about grief and in efforts to inspire others, adding that no one should put a time limit on moving on with your life after losing someone you love so much.
"We all do it differently in different ways," she wrote.
The post is filled with fans thanking her for sharing and sending condolences on her immense loss.
McCain continues to share the late icon's impact on her life, wishing co-host Whoopi Goldberg a happy birthday last week, posting a sweet picture of her father visiting the set of "The View."
"I don’t know what I would do without you. Thank you for your friendship to both me and my family. You are a ball of love and light in this crazy world and I am so grateful for you," she wrote to Goldberg.
John McCain, a Vietnam War hero and one of the most distinctive figures in modern American politics, died at the age of 81 this past August.
His passing sent out shockwaves of grief that cut across politics, and he lay in state in the Capitol, an honor reserved only for major American figures.