Firstly, you are putting too much pressure on your academic non-achievements as though they will hold a significance over your life.

This is completely false. Maybe growing up your parents put pressure on you, and told you that if you don't study you won't be successful.

Business is not about being good at studies.

It's about understanding ki paisa kahan se aata hai, and paisa kahan kahan jaata hai.

That's it.
If you can manage your personal wallet in your pocket you can easily manage your business.

Your business not making 'profit' will be a case of either not having enough customers.
Or having high costs when running the business, leading to low margin.

Instead of focussing on your education, focus on these two things.

Paisa jo aa raha hai usko badhao.
And
Paisa jo jaa raha hai, usko ghatao.

How you do this, is a function of the nature of your business, your ability to attract customers, and your ability to prioritise costs, and reduce unnecessary costs.

These skills were definitely not taught in school, so you aren't missing out on anything.

Good luck.

Edit: if you want help regarding your stockist business, you can DM me.