I am sorry you are HIV positive. That is difficult for someone to accept, especially at such a young age. I, myself, have a disability. For me the purpose of life is this:
I believe that God created us all to make a decision in this life. That's what this life is about. We either choose to accept Jesus as our Lord and Savior or we reject Christ as our Savior. Our decision will determine where we spend eternity.
John 3:16-17 16 For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life. 17 For God did not send His Son into the world to condemn the world, but that the world through Him might be saved.