Composition is a special game. You either 'have it' or you don't. I am one of the lucky ones and my teacher literally employed me in lessons to help guide the other students. It is almost impossible to teach if you (or the student) don't have some natural ability, however, there are things you can do. I found that a lot of students improved vastly after listening music related to the compositional style they were working on. Don't be afraid to imitate ideas from other composers (do not copy though). Ask your teacher for help, but if you don't like what they have written, don't use it. Remember, composition is a creative exercise and requires your own ideas. Play around on the keyboard or guitar and think of a Melody for example. Work on the chords afterwards. The one thing my teacher always got wrong was chords first, then Melody. If you're struggling to think of something try either way (I find it much easier to think of a Melody first however). Have you tried humming or whistling ideas in your quiet time? Works insanely well for me. You will get a 'light bulb moment' eventually. Good luck!