Your attempt is grammatical, but I think your teacher thought it was unnecessarily grandiose and stiff. (I think you already know the difference between wago-and-kango.) Although we see 希望 used in songs and documentary videos all the time, 希望 is not a word we use on a regular basis. When you want to say "I hope so" or such in a daily situation, usually you should use ～たい, ～たいと思う, ～(だ)といいですね, ～れば良いと思います, etc.
Still, you can use 希望 when you seriously declare your choice. It's perfectly fine to say 私の将来の希望は教師になることです or 将来看護師になることを希望しています in an interview or such. If you have a chance to write a Japanese curriculum vitae, you may see 本人希望記入欄. Japanese high school students often fill a form called 進路希望調査 to tell teachers their intended future course.