I’m sorry this is so stressful for you. One way to manage it is to try to see the situation sympathetically from your parents’ point of view. My guess is that you are not a burden. Your parents feel they missed opportunities that they want very much for you to have. They are so focused on making a better life possible for you that they have put extra pressure on you without meaning to.
Understand that the “pressure” from your parents is really a cover for their fear that you will repeat their situation and deprive yourself of the experiences they so wish they had had. They love you so much that they want you to have what they did not. Sadly, their way of loving is making you anxious.
I don’t think you will be able to get them to change. What you can change is how you receive their pressure. If you consider it as well-intended support gone wrong, maybe you won’t feel so bad.
By the way: It’s not a bad idea at all to try for scholarships. If you can see the world by attending a university in another country, you will enrich your own life immeasurably. If you do get accepted, don’t present it to your parents as needing to get away from their awful pressure. Instead, tell them how grateful you are that they have made it possible for you to do something they didn’t.
Meanwhile, do respect your parents’ boundaries about what is and is not appropriate to share with other people. It sounds to me like they are more private than you are. As long as you are accepting their support, it makes sense to accept some reasonable rules.
As for the ADHD: ADHD can be managed. I have had many successful students at the university where I teach who have used it to their advantage. Go to the “Find Help” tab on our homepage. Click on “forums”. Join the forum for ADHD. People there support and encourage each other and give each other strategies for managing it.
I wish you well.