Not everyone gets the parents they would like to have. At 25, you know who your folks are and how they are likely to respond to you. They are not likely to change, no matter how much you wish it, argue about it, or criticize them for it.
My guess is that, to them, you look like you are doing fine in contrast to your brother. Their emotional energy has been tied up in trying to get him on the right track. They don’t have enough left over to offer you more than their confidence that you will figure things out for yourself. That is a kind of support.
Although this may be difficult and painful for you, it is not unusual. Often the siblings of kids who are chronically physically or mentally ill or who are constantly in trouble feel neglected or like their needs take second place. The child in trouble gets most of the support because that is where most of the support is needed.
I suggest you find a way to be more compassionate toward your folks, especially since they both tend to be introverts. They are dealing with things as best they can. They didn’t ask for a delinquent kid and it’s all they can do to deal with the feelings and practical problems that go with having one.
Instead, love them for who they are and find other adults to turn to for advice and more direct support. There may be someone in the extended family who can both help you understand your parents and offer you the help you seek. If not, start making friends with teachers and the parents of your friends. There are many good-hearted and wise older folks who would be happy to listen to you and to offer you the encouragement and support you want as you move forward in life.
I wish you well.