Weight loss experience to give me motivation , im only 17.?

Hey so im 5'8" 160 and want to be 130 to 138 and I need to feel like with my BEST effort I can accopmlish this by september or october , the change will be permanent but concidering the work I need to be sure of my reward , based on experience (not data from scientific experiments) is this an exceptional goal , if not what is and please tell me your info and ****...