"for meditation you are supposed to be free of such thoughts"

This a pernicious falsehood. It's possible to achieve, but even most advanced meditators aren't spending long stretches of time thought-free. Wrestling with your concentration and being aware of what you're experiencing is meditation.

It's pernicious because it leads people to believe that they're not any good at meditating, since they look at their mind and are aghast at how cluttered and chaotic it is. The fact that you now start to see it, IS meditation.

You were doing just fine.

A lot depends on how you define "thought". If you define "thought" as any kind of mental experience (including "sensory" experiences such as simply experiencing the external world), then I would agree that our minds are "cluttered and chaotic", as they are filled with this experience whenever we are conscious.

On the other hand, if you define "thought" as a sort of verbal "inner dialogue", then I think it is possible to go through long periods of time without it (both in meditation and in more ordinary states of consciousness).

I am only a begginer at meditation, so I can not speak from personal experience regarding what deep, committed practice in meditation could achieve, but I have read many accounts of people in the Buddhist and Hindu traditions claiming to get beyond any kind of conceptualization or "thinking".

Certainly, there are also traditions which claim something like "nirvana is samsara" (that the "true" world or reality is the same as the "illusory" world or reality, in some profound sense that only the enlightened individual can grasp), that even in the enlightened state, what one does is "chop wood, carry water", same as in the non-enlightened state. So, some could argue, even deep meditative states could be just as "cluttered and chaotic" as ordinary states of consciousness. But this is not the only or necessarily even the most dominant view.

  I just couldn't concentrate.
  Lots of things would come to mind. Revenge, sex, regret, 
  frustrations, hope, plans and a lot just used to happen in
  mind at that time. More than usual. More than it would
  usually come to my mind.

I'm only just beginning to learn about meditation but in most forms of meditation these thoughts are perfectly normal. Mindfulness meditation stresses that these thoughts are okay. One of the first things you learn is to accept these thoughts without judging them or judging yourself.

If you ever give it another try, give your mind permission to go wherever it likes. What will your mind feel like when you're not fighting with it and trying to make it think (or not think) about particular things? It may be rewarding to find out, or at least relaxing.

Best wishes!

When you notice that you are thinking, go back to the breath. You don't go back to the breath so that you can meditate, going back to the breath is meditating. It can happen dozens, even hundreds of times during a session. That's the point, in as much as there is a point.

I found that whatever thought is eagerly bubbling to the top is probably something I should think about why it's surfacing. After you deal with the issue (which may take a while) it is less buoyant and bubbles up less.

However, I do meditation in the sense of asking God to communicate and then listening for him. It's even more helpful to ask him what he wants you to change and then listen. I cannot speak to what is helpful for Eastern meditation, though.

I think you're going to need to deal with the buoyant thoughts (regardless of whether you are religious or not), though, otherwise what is underlying them is going to drive your actions without you realizing it.

The guidelines that I've followed always say not to fight these thoughts, but to let them pass over you: that they are inevitable, but you should not give your energy to deal with them and to let them pass on their own

Ideally you use meditation as a tool to quiet those thoughts.