Hi, welcome
In a way you are describing a key part of life in your post that needs to be overcome. With a low mark of 17% in my view your biggest challenge isnt your techer nor your parents, its with you. Your challenge is to aim for a significant mark higher than 17% - say 30% which is a realistic improvement. If you then get 40% then you have more than succeeded but that isnt the end, the next challenge is 50%+
In life with many topics the easy way is to give up. This is the normal difference from a teenager to an adult- to face the challenges of your life in a real way, an achievable way and to improve but not expect yourself to be a academic in everything you do.
Motivation is lacking in many people, but then there is unrealistic motivation. I recall being a salesman for insurance and the goals they place don me were unattainable for me. I had improved my sales but nowhere near the level where they were content so I left that field and excelled in investigations for example. So yes it is also realistic to drop a subject when the opportunity comes along but until then if that isnt a current option then face these challenges with the view that you will improve...
I hope that helps
TonyWK
