I read your concerns.
You seem to have a deep interest in the concepts of impermanence and emptiness. These teachings certainly support the heart during difficult times. However, I understand the trouble of feeling empty when having fun.
First, it is important not to understand the idea of impermanence in isolation, but to grasp it together with the other three concepts.
1. Everything is impermanent: everything changes
2. Lawless Ego: There is no absolute fixed ego
3. Everything Is Hard: This world often doesn't turn out the way you want
4. Nirvana Silence: A quiet state of mind is safe
It is only when these four are included as a set that the essence of Buddhist teachings can be understood.
It is necessary to cherish this moment because everything has changed and there is a lot of suffering. When it's fun, it's important to fully enjoy that moment.
Instead of feeling sad thinking “this fun will end someday,” it is only by enjoying the present to the fullest that we can put the teachings of Buddhism into practice.
The concept of the sky is similar. Precisely because there is no fixed entity, our existence is a combination of components of that moment, and that is why every moment is precious.
In other words, when you're having fun or being happy, you don't need to think about imperfections or the sky. Rather, it's important to genuinely enjoy the moment. When it's hard, I think “this will end someday,” and when it's fun, I think “let's enjoy this moment.” By doing so, life as a whole can move in a direction where there is less suffering.
Buddhist teachings are meant to make our lives richer and happier. Don't feel empty when you're having fun; enjoy that joy deeply. That is truly understanding and putting into practice the teachings of impermanence and emptiness.
Please continue to deepen your learning of Buddhism and practice it in your daily life. I sincerely hope that your life will be richer and happier.