Hi Janses! I am sure you are not the only person who is having this problem. I believe that a lot of people get stuck at that same place when they want something too much.
You said it when you described your belief system around the big thing you want. The fact that you think you won't get it, you don't deserve it or are afraid of what will happen when you do get it, is the main reason why people don't manifest things they really want in life.
I wrote a couple articles that explain how to turn that situation around. The first article I explain what to do when you are afraid of manifesting your dreams. It's called How to apply the secret to business and get results. That article goes through how to use visualization to build up to a dream or goal you want to create when you are in fear. I think you will find it very helpful.
Another article I wrote that also deals with the same problem you are having is, The Law of Attraction what they forgot to tell you This article breaks down how to put the law of attraction in use so you do get the results you are looking for.
And last but not least I have created wonderful free Mp3 downloads that will guide you easily into visualizing something you want in your life. Free Mp3 Mediation and visualization downloads They are all great but for you I suggest starting with Creating your ideal life.
The one final thought I have is anytime you ask for something always be open to accepting that maybe just maybe whatever it is you are asking for the Universe has something better in store. So finish your request with, May this or something better now manifest for me in divine appropriate timing. And then trust Janses that it will.
I wish for you all the happiness and success the Universe has to offer!