Good job! I am sorry that your parents are not being as supportive or understanding as they could be, but you made a huge first step! My family is a bit different, since I am the fourth person in my immediate family to be treated for bipolar or major depression, but I know it is very common for parents to not want to admit there is anything wrong with there children.
Don't let them bring you down, they do not understand what you are going through and really they never will. It is not their decision, it is yours, and you are ultimately responsible for your own health. There is still a lot to come, but the hard part is over. Now make that appointment!