Ever since I had a brain tumor when I was 16, I feel the same way. Everything feels so far away. Nothing seems real, so therefore, I never get what I want out of what I expect to. It's not easy to live like this because it makes it hard to choose what to do on an emotional level. It's been really hard for me to overcome this, and it is a work in progress. From time to time, I have that empty feeling, like nothing. As you describe it, blankness. Almost like being in a fog. I've been to doctors and they all say there is nothing they can do.
The good news is that for me it is not always there. Some days it is worse than others. I understand to some extent how you feel (or don't feel). Good luck in feeling better. Think positive and even if you don't feel you're getting all you can out of life, you can work towards it.