Well, good news, that’s perfectly normal. Below is my personal process, in detail.
1- I make an outline of all the events I want to include in the book, trying to put them in chronological order (months, years). For some reason I always do this on paper, in pencil. Below is what one of my outlines look like. It wouldn’t make any sense even if it were in just one language, and it’s not ;P
2-Then I start writing on my computer. This is no pleasure ride. The writing is coarse, dialogues drag, descriptions are irritating. Nothing works. Once in a while I get into it (those typically will be the parts that end up staying in the book) but mostly I have to force myself to keep going, because IT SUCKS. As I do this I add notes whenever I realize I forgot something on the outline. I will add it later. For now, just keep going, get it all out.
4-Typically, toward the end of the first draft I become excited because I start to see where the book is going, which topics I will need to develop and which others I will boot out of the draft (and likely move to a different novel). I can’t see the novel till the first draft is done, I can’t see what characters will play a part in it and which ones will need to be slaughtered. You have to go through with it, even if it sucks, even if you’re ashamed of it, even if you have to get yourself off tumblr every twenty minutes because you keep getting distracted. JUST. KEEP. WRITING.
5-And then? You survived the first draft! Now the fun part comes. Now that you know what’s relevant to your plot and you have a path, your main plot, you can start to polish dialogue, description, and everything else. Now you know which feelings to build toward, which seeds to plant early on etcetera. The rest will be still hard work, but fun, because you feel like you’re making your work better. You’re finally sculpting your work of art. Just get there, plow through!