Incoherent Meditations

Seemingly, despite my questions, I still am encountering great difficulties. I've been meditating for perhaps 1-2 years in a haphazard fashion, on the metro, walking places, while doing things. Perhaps the word "meditation" is inappropriate, it was more like a mindfulness or perhaps a mixture of different types of reasoning, contemplation and attempts at realizing certain facts. Overall, I feel like I've accomplished absolutely nothing in these two years, and that I've wasted much time. I would say the only thing I want now is to be able to stop all this, whether to meditate properly, or even to understand how to reverse the conditioning that I unwittingly imposed upon myself. I'm asking if anyone knows or conjectures a means by which I could achieve this, and perhaps some tips on what I should avoid doing to create this massive incoherence in my mind.