Parsing Only Certain Keys in a YAML File in Golang

I have a YAML file that I am reading in in Golang and unmarshaling to a struct. The file contains several keys, but I only need certain ones. What I am finding is that if I place the keys that aren't needed for this application at the bottom of the YAML file, everything works as expected, but if the keys are in random order, the unmarshaling / parsing returns unexpected values. For example:

Sample Simple YAML file:

---
  cat_name: rusty
  dog_name: billy
  cat_food: Purina
  dog_food: Blue
  cat_rescued: true
  dog_rescued: false
  cat_age: 4
  dog_age: 6
  happy: true

type MyStruct struct {
    Happy  bool  `yaml:"happy"`
    CatName  string  `yaml:"cat_name"`
    CatAge  int  `yaml:"cat_age"`
}

Code that does the unmarshaling:

data, err := ioutil.ReadFile(filename)
    if err != nil {
        return nil, fmt.Errorf("Could not read file %s. An error has occurred: %w", filename, err)
    }

    params := MyStruct{}
    if err = yaml.Unmarshal(data, &params); err != nil {
        return nil, fmt.Errorf("could not parse yaml from file. %w", err)
    }

    return &params, nil

What I am finding is that, I will get back the correct CatName, but that the other two fields (Happy and CatAge) will be false and 0, respectively.

However, if I change the ordering of the keys in the yaml file so that the three keys that I need for MyStruct are the top three in the YAML file, I will get back the expected data of true and 4.

I am pretty new to Golang and am wondering, after doing a lot of searching and experimentation, what I am missing? I am using the https://github.com/goccy/go-yaml library to do the unmarshaling. Is it expected when unmarshaling YAML to a struct that the order of the keys in the YAML file are in the same order as the struct fields? Thanks in advance.