Originally Posted by: polanskyI used to be a drummer, when I sat down in my kit I could "see" things, like I can see music in those drums, but now I'm in a struggle with the guitar.[/QUOTE]
This is where music comes from! That vision is a gift.
Treasure it; foster it; care for it and help it grow.

Originally Posted by: polanskyMy teacher (and former guitar player of my band) was teaching me, he really knows a lot, he is a gifted guitar player (now he's a bit rusty but it's a fisical thing), he wanted me to learn like the "right way", you know? like first the notes, a bit of finger independence, then started with a little of scales theory, and then, some cords... sounds OK right?.[/QUOTE]
NO! :mad:
This is the path that leads to playing other people's music, without knowing how to express your own voice.

Originally Posted by: polanskyMusic theory is insane, I get some things but sometimes it feels like so much to know only to play like really basic stuff, and then the fisical thing, my fingers doesn't seem to respond, sometimes I can move with comfort and sometimes I'm stiff like a wood board.

Of course! Music theory is valuable knowledge, but it must always be servant to the Muse; never the Master.

Theory is like the rules of grammar in language. You must know these rules in order to express yourself clearly; to be understood by all who hear you.

But you must have something to say. Without that, grammar and vocabulary just give you better ways in which to say nothing of importance. Feel the music within you. Let that feeling flow from you into the guitar. When you find limitations in your ability to transfer those feelings, then you can seek instruction in theory and technique.

[QUOTE=polansky]Quiting has passed trough my mind, and it really gets to me cause I want to do this, I wanna be on a stage, I miss that, I need it.

YES! Musicians, like any other true artists, do what they do, not because they can, but because they must! You can not truly quit. You "used to be a drummer", and now you are attempting the guitar. You are searching for a way to express what is in you. Even if you move on, still searching, and try a different instrument, you are always moving forward towards finding your voice.
[QUOTE=polansky]Is it normal to feel like this?, If practice is the point... how long should I do it?, and should I start right away with my 7 string or should I stick to my 6 string for a while?... I'm really confused. Help.

Stick with the 6-string for now. A 7-string guitar offers additional range for an accomplished player, but I think it is unnecessary for someone who is just starting to find their way.

And yes, such feelings are normal. I think you need to simplify your life a bit.

Choose a song that you know well enough to sing, and learn how to play the chords for it. Then learn how to play the melody. This song will serve as both a goal and an inspiration. And in learning it, you will acquire the physical dexterity, the knowledge of music theory, and the appreciation of compositional skills that you will make use of for the rest of your musical journey.