Disappointment and fixation on one "large" unmanifested intention puts blinders on your eyes and you miss all of the "smaller" things you are attracting. It's these "small" things that lay the foundation of our faith in the law of attraction.
Nothing will help you build faith in the process of attracting or manifesting other than actually receiving. As you attract and receive things, your belief will grow and you will have more faith in the law of attraction. This will allow you to attract even "larger" things.