There’s always more or different when you do a PhD.
You could have done more of something in your research. You could have done something in a different way.
It’s valid to be concerned about it as you write up your thesis and prepare for your viva. It’s reasonable to expect that examiners might ask about more and different when they meet with you.
Focus first on what you did. The fact that there are other options rests on you necessarily doing something.
Explore why you did what you did rather than something else. In your preparation, take time to be clear and articulate your reasons.
Then in the viva take time to listen to your examiners’ questions. Don’t dismiss them, but do clearly demonstrate the contribution that you’ve made.
Alternatives might be possible but focus on the actual work you’ve done and the difference it makes.