I just played a game and I won, it was really close and I would have won with 1 point more, if I had not played that last move.
But I know I made some mistakes (I just don't know where^^).
I feel like I have gotten stronger and maybe I can call mayself a 18k now?

This is my first game as a KGS 16k, I was black. My opponent was a 14k so I had 2 stones more.
At the end of the game and when I played in the middle I felt like I was losing, the center looked too big for white.
Is there a easy way to count points fast during a game? I thought I had lost and was surprised to see that I have won.

Typically the player that has all four sides and corners, unless they are particularly low, is going to beat a large central Moyo.

A quick way to estimate anything that is roughly square/rectangular is to count out two sides and multiply them (if using Japanese rules, make sure you aren't counting the borders). That gives me about [9*11 + 5*3] 115 points for White's moyo. Using the same method I count your territory at about 108 points. (Left side = [10*2] 20, Lower Side = [17*3] 49, Right Middle =
[Manually counted] 15, Upper Right = [3*8] 24)

Keeping in mind there's a margin of error for such rough counting and it comes out to a close enough game I wouldn't want to rely on such a counting method.

EDIT: Manually counting, it was actually 109 points for White's moyo and 111 points for your Territory. If you want increased accuracy, reduce the estimated score by the number of your own stones floating in your own territory minus the number of the enemy's stones doing the same. It's usually quicker to do that than to count all the empty intersections.

To the former, call yourself 16k! That's what you won as

To the latter, the easiest way to count points fast is (IMO) to learn how to do it properly and then get good at it. Practicing, even not very much, rapidly makes you faster and more accurate - especially as you start to remember (even subconsciously) some shapes. It doesn't take much effort to get started. DrStraw's counting lessons at http://senseis.xmp.net/?SteveFawthrop%2FCounting are fantastic...I only ever did the first one, but it got me this far, and I'm sure I'm missing out by not doing the rest!

Just some variations for B move 22.

professionals can count pretty accurately under 1 minute.
i can count accurately given one ~ two minute.

counting end of the game:
in my opinion if you count 1000 game (really counting throughout whole game) then you will be proficient at it.
i think it is like playing piano. more you practice you will be better at it.

counting in the middle:
it will take reading skills plus patience.
professionals can make access the board in the middle very accurately.
most game i can access the board in the middle within 5 to 10 points.
it will come as you get stronger.

_________________
"The more we think we know about
The greater the unknown"
Words by neil peart, music by geddy lee and alex lifeson

Your fuseki was good enough to be SDK. Your tactical play - when you actually chose to fight - looked good enough for an SDK.
The recurring problem was between those two: as soon as the middle game began and the stones began getting close to each other, you repeatedly backed down when you could have had a fight that you could have won.

In particular, look at my comments to moves 18, 36, 50, 104, and 124 in the diagram below. White made overplays, and you folded, despite the fact that your fighting skills are good enough to make white regret his overplays. You only fought when you were absolutely forced to, when white invaded in the lower left and lower right corners.
Change this one habit and you will be SDK in a month.

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Thanks everyone for your comments, I try to remember all that

@Joaz Banbeck: Thanks that really helps me.
It is true that I try to avoid fights because I'm not really sure that I can win.
I actually thought that my fuseki was not really good, but it seems I have to focus my studies on fighting first.


Are there any good books or online ressources about fighting?

I'd just do some tsumego and simply fight a lot in your games. Fighting is fun.

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Sanity is for the weak.

"Attack and Kill" by 'Killer' Kato Masao. ( It might be aimed at players a bit stronger than you, but I'd give it a try )

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One other thing that I forgot to mention: when you are involved in a liberties race, with each of you having outside liberties, and some inside liberties being common, best technique is usually to fill his ouside liberties first, not the common liberties. There is an example of this in your game: 76 should be at G1. Then he does not get the ko, and you win the fight outright.

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Ah yes you are right, thanks I didn't think about inside and outside liberties at that moment.
A ko can get dangerous^^