I agree with your mom. College admissions officers are used to seeing a bunch of people pad their resume around junior year when students being to panic at their lack of leadership roles.
It’s better you do not start another club, seeing as (according to your other thread) you are already playing active roles in 2-4 other clubs and sports. Don’t spread yourself out too thin! If colleges see that you are doing too much, they may assume that you didn’t actually play that big of a role in the activities you named–some sceptical admissions officers go as far as to call your counsellor and verify that you were indeed part of those many school activities (not that I’m doubting your role in each of those activities).
If anything, focus on strengthening your outside of school activities. It looks like you’ve been doing some open-source? Build your GitHub and put out apps onto the app store. Learn new languages because there are A TON (Vue.JS, React, React Native, Ruby, C++, Swift, Java, just to name a few.) Offer to code websites for non-profits and apply to work at a few startups! You don’t need to start a club on campus to show that you care about CS.