Re-evaluate your goals. Progress will come slowly but it will come. Given the right sort of determination and consistent effort, your goals may eventually come into clear view. Even before you achieve your goals however, you may find that your goals are in need of re-evaluation. By this point, you'll have put far more time and thought into manifesting your desires than you did in the planning stages. With that in mind, you may have a clearer idea of what you actually want now than you did.
A psychology professor at Yale recently asked her undergraduate students to complete an "art therapy" exercise. She passed out paper and crayons, and asked them to draw a picture of what they thought their life was going to look like. Upon receiving the assignments, she was shocked to see most of the pictures were images of hopelessness -- dark colors, falling off of a cliff, hitting a brick wall, or being generally unfulfilled. If our "best and our brightest" are afraid to dream in their early twenties, something must be done.
You can choose to be happy by choosing to think positive thoughts. Focus on what you are happy about. Imagine how you would feel if your desire is a reality now. Allow yourself to feel the excitement, exhilaration, joy, gratitude and happiness now. This feelings are what you remember when you re intending your desired reality as they become your set point. Whenever you feel good or happy, you become a powerful magnet to rapidly attract your desire. Happiness is a choice, you can choose to be happy in any moment.
You claim that "positive thoughts always resulting in positive things" is not the basis of the LOA. In part you are correct. The foundational basis in science, as I alluded to in the article was that thought stuff particles travel through ether (not air) and interact with formless stuff to create whatever it is that you are thinking about. This was how "the law" started.

How To Manifest What I Desire