write a letter to my girl

There's a beautiful tradition in my family parents write letters to their children every 5 years to celebrate their successes and mention sweet little details and write down something that kid won't remember but you personally find important, funny and just generally worth keeping. These letters are kept until some day in the future. Like I got married when I was 22 and my father gave them to me after the wedding. I'm a father to a beautiful girl and means a world to me. She's soon to be 5, I wrote a letter to her the day she was born — I was the happiest man on this planet and it was so easy to do. Of course, I love my daughter but this year was hard on us and I can't find words. I feel so tired and so upset all the time. These aren't the feelings that I'd want to share and it just happens every time I try to start writing. I feel so ashamed. Like if I can't find any words to say how much I love my own daughter what I even am as a person. what's so wrong and how to fix this?