Master bedroom design

Background and higher vision

Here is the really first project that we are doing from zero and have actually taken time to plan it and think through. 
The bedroom is roughly 15m2. It has two windows, one of them has balcony door together with it. The windows are not tall from floor, just regular ones. At the moment we have just whitish walls and one big bed in the room. Windows have window blinds that we got first thing before we moved in. 
As I am mostly the mastermind in this project and just feeding the ideas to the other half so I can see what his reaction is going to be, I am feeling the pressure to succeed and actually achieve what I have in mind. No idea, how it will actually turn out. 

I am planning in the first phase:

• redo the walls with wallpaper
• get proper curtains
• get full carpet on the floor
• replace the bed and get bedspread

Second phase will be about furniture such as:

• nightstands
• dresser with drawers
• night lamps

But the truth is that I have no real experience in decorating and designing the interior and it is going to be my very first. No experience, no training, nothing -  only thing I have is my own instinct and logic and imagination and taste that I try to detect.
The funny fact is about why I actually agreed to start with out bedroom. I believed that other things in the house are more important and our bedroom can  pretty much be the last one. Little bit after last Christmas we decided to buy the lamp that I had checked out some time ago. The journey to find the lamp has been also very long and we had been keeping our eyes open long time to find one that we both like. Finally when I found the one I liked, not just settled with, intalled it and replaced the bulb, we ended up in the situation when I no longer could not ignore the depressing look of the room. The lamp was actually screaming out loud for us to get the room done. 

I had definately been fantazising over the years what I like and this has been dreaming mostly. At the moment when we actually reached the decision that we are going to work on our bedroom first, I started to put actual effort to trying to figure out what do I actually want our bedroom to look like. One thing that I have concluded is that in real life to start planning your bedroom, is not easy at all once you actually start doing it. As long as you are just dreaming and fantazising, it seems so simple. 
My main challenge at first was to choose the bigger picture to bring the design together. 
I have been scrolling and searching the Pinterest and it is the best place to get ideas and at the same time this is the place where you get your head messed up because there are sooooo many nice things and good ideas and perfect solutions but you can only choose one. 
Over the time I have had in mind something brownish-goldish, white, grey, darker and ligher. Also some little bit extreme solutions for my taste look very cool so they make me try it out as well. 
So after considering different ways how to continue, I decided to go with grey. 
I am rather traditional type of person and don't feel confortable to experiment with extreme solutions. I like modest approach that a lot of people could think of as boring. I would rather add some cool details but cannot do that either before the bigger visual is not finished. For example, I cannot plan little details such as candles or picture frames etc before I don't have colors and most of the solution ready. Then I can start thinking about how to add details. 

Starting points to stick with:

I knew from the beginning that I prefer modest approach but the feeling of the room has to be cozy and warm not so much modern and cold and not too proper.

 I also knew that for master bedroom I prefer to have wallpaper because for me this is helping to make it cozier. 

I also knew that I need two sets of curtains (tulle curtain and side curtain).

I have always been wanting the carpet that covers entire floor because this also is the symbol of cozyness for me. 

I knew that the colors of the room have to match together perfectly. 

Also knew that I love the natural light, so the overall impression of the room has to be rather light.