They say, when you accept the problem , you have won half the battle. So in your case half the battle is won.
As a student your prime duty is studies , so your parents concerns are justified.
Self goals and self punishment - this is the best way to get over your problem.
Sit down today, and chalk out a time table fog the next week.
Try a reasonable time table initially.
Eg : I will finish one chapter everyday.
In case you fail to achieve your target - then you will not watch porn that day. If you do achieve your target, you can watch porn - guilt free
Next Steps
try these recommendations for two weeks. if they don't work visit a counselor in person