Hi Esther! First of all, it's amazing that you're focused on leadership. However, there are all types of leaders, and just because you're not on a club or organization's committee or board doesn't mean that you're not a leader.
Employers aren't going to look at your resume and think "oh jeez, Esther wasn't a leader of any club." They are going to be able to see if you demonstrated leadership potential in everything that you did.
The best way to demonstrate leadership potential is by taking small actions and setting an example for others. In your clubs, are you focused just on becoming a leader because you want to be recognized as a leader? If that's your motivation, people will see that it's recognition that you want and not that you have leadership potential.
A better way to show leadership potential is by setting a great example for others and empowering the club and its members to be successful. If you approach the clubs with the mindset of setting an example, you can start small and then work your way up to being on a committee or becoming a board member. Think of how you can help people in the club. Can you volunteer to take notes at meetings? Can you offer to assist the leader of the club with a project?
If you do that for a while and you still don't feel like you're making progress, take a committee member or a board member out to coffee! Ask them what you could be doing better. Making yourself open to feedback (and asking other's opinions) is one of the quickest ways to be successful!
Finally, while it's an advanced article, this is one of the best ways to think about being a leader: https://hbr.org/2015/09/to-become-a-leader-think-beyond-your-role