Here is the problem. I really did something wrong to my girlfriend and now she wants some time (a week or two, even more) to be alone to pack up her mind to see what is the best for her, that it's possible to be with me again or not. She doubts about my true feeling to her. She thinks I've pretended to love her. From now on, I have to wait for her for at least a week or more as I mentioned before.

#1) Is it rational to text her after a few days before finishing the first week, to question her feelings and the result of her thoughts?
#2) Suppose that the first week just finished and I want to make my move...
- Shall I text her or call her?
- What's my opening sentence?
- Shall I mention the problem again and ask her about what was going on in her mind and what the result is? Or pretend somehow nothing was happened?

You don't do anything. It is all in her hands now.

I don't know what you did, but it must have been pretty serious.

Sure, sure...contact her even though she told you not to. Without a doubt doing that will make her decide so much quicker. Probably not the decision that you want to hear though.

Sounds like you will be lucky if she decides to come back to you.

First, "give me time" is almost always just a way of saying, it is over and I do not want to fight about it. I just want you to go away, and not bother me again.

If not, the worst thing, you can do, is contact her at all, for a few weeks.

If she does not contact you, it is over.

At this point assume it is over, and go in that direction.

How old are you? How long have you been together? What could a guy do to make his girl dump him and need time to think? Oh you didn't know you were dumped?

Those are important details if you want some advice I would think, don't you? Otherwise hope for the best and plan for the worst.

No, that would be irrational as she asked you for space but you aren't giving it to her.

Neither, the ball is in her court. You leave her alone until she contacts you.

Depends on what she says when she calls you.

Exactly what was the "problem?"

Despite what appears to be an almost alarming lack of awareness on your part, just in the few sentences you wrote here, I am going to suggest that at the end of a week you DO do something indirect.
You do NOT text her, email her, call her, or knock on her door. You do not ask such totally clueless things as what is 'going on in her mind' and you do not pretend that nothing happened. You aren't getting that those are both stupid and counterproductive.
What you CAN do as a last gasp effort to show that you are sorry (are you?) and that you care (do you?) is send her flowers and a hand written note. You do it through a third party or delivery service.
I don't have much hope that you will know what to write, however. And no one can or should tell you.
Good luck.