For a while now, I've been doing both school and training as an athlete (though I haven't done anything professionally since I don't have the time). I really enjoy the sport I'm doing and I even met someone who was willing to refer me to a a professional (even Olympian) athlete to coach me. However, I could not meet him since school started and I would be out of the city. Since then, I've regretted not asking my mother to let me stay a day longer to meet with this Olympian and see how far, or even if I had the potential to continue with the sport.
What's worse is that my self-esteem in what I'm studying in school is dropping. So far, I haven't had any boundaries with studying and grades. But I've had conversations with my friends and other acquaintances of their futures with their studies. They seem truly with passionate with their subject and wish to go to higher levels. I realized that I had no such passion, and that I was only going to school because my mother wanted me to. I neither felt bothered with my program nor was it something I enjoyed; it was merely something I had to attend if I wanted to "make money and have a future".
Yesterday, my mother had a serious conversation with me about dropping the sport. She said that I didn't have time to continue the sport (since it would only get harder and I wasn't the smartest of students either) and because I haven't done it professionally. I found this unfair, and unconsciously argued with her that the sport was important to me and that I was only going to school for her rather than myself. I was surprised to realize how incredibly unhappy I was living like this as I have not made my decision based on what I wanted and what I should follow.
I really do not wish to drop the sport, but I do not know how I can make it professionally to keep it as part of my life. Or should I look at reality and give up on it?
What should I do?
I would greatly appreciate some advice, please!

If it's something you love, stick with it. Life becomes much more worth living, and much better if you keep things you love around you. You can make a lot of money in the sport industry, depending on skill level, and if you had the chance to train with an Olympian you must be pretty good. Hope this helps!

It also depends on the degree. Getting a degree doesn't always equal success and a job. Some degrees require major commitment and dedication.

Maybe go to a trade school and play the sport as a hobby?

I started studying economics after dropping out of school because of my mum. At first, I really thought I wanted to change something, but the truth was that I let myself be manipulated by my mother. I do not say that it was here intention, but our parents think differently, the world has changed drastically, and even if our parents just want the best for us they do not realize that the skillset they want to give you on your way is outdated. They want us to have a save job, a good income, healthcare insurance, etc, but I do not think that it matters. I really regret that I did not have the courage to say screw you world I do what I am passionate about, and if it is sport than stick with that, it is maybe hard, but deciding to go the unconventional path though your mum is against you, shows you that you are serious about it, and maybe your mum will understand too. I personally really believe in living without any regret, do not play the save game, you know why? The game is never save, even if you have the best plan something can go wrong. Worship the short amount of time you have on this planet and try to enjoy it, risk whatever it takes to reach your dreams, be a dreamer and live everyday so that if you would be gone tomorrow you wouldn't regret how you have spent your day, cause you would have done something worth it.
Have courage!

I will definitely take all of your advice to heart!
Thank you so much, I truly appreciate the help!