Your parents responded in a rather expected way. They probably did not see it coming at all, so of course they'll 'miss their daughter' and the likes. It will take time for them to get used to the idea. Transexuality is still a rare 'condition', and it is usually the last thing parents suspect (the first thing that usually jumps to mind is being gay, or having other issues, not being trans).
That being said, it is important that you keep communicating with your parents. You seem like a very eloquent person, especially when considering your age, so talk to your parents. Ask them if they really want to hold on to the lie you have been living. Ask them why they do not with to see the real you, or want you to be happy. After all, no one wants to live a lie, not being him or herself.
It may also help to educate your parents a little. I do not know what they know about transsexuality, but most people have the wrong idea with it. Think of crossdressers and the like. Nothing wrong with that, but it creates the wrong image for transsexuals. We do not cross dress. We do not want to be a boy. We -are- boys. Maybe show them videos or pictures of successfull trans guys, and edcuate them a little on how things would go, starting with a therapist.
Good luck with this! Parents are usually one of the hardest hurdles in the process to overcome.