I don't want this to end up being very long, but it's something that has stressed me out for a long time.

  Basically, I came out 11 months ago to a family friend and to my mother, though I've known I was trans since long before then. I've gone by a nickname for a long time since I didn't feel ready to jump right into being a man, and it seemed more logical, but as time has passed I've come to hate the nickname... It's been used to mock me, and I feel like it's something I want to leave in the past of my transition. My mother refuses to call me anything but my birthname and that nickname, though I've finally come up with a name that seemed to "click" immediately...

   The past few weeks I've had a vicious virus, and I've been borderline bedridden (hence my absence from the forum) so I've had a lot of time to think over things. I've been sleeping a lot and I've been having strange, almost cryptic dreams where I'm living another life. In the first one, I'm surrounded by pink silk that flows around me, and there's a bright light. A woman in a hijab comes from it, with a cap and a cloak. She puts the cap and cloak on me, and says,
"You're a man now, Adnan."
I keep having these dreams where I'm Adnan, going through his life, through raising children and other milestones. Then I realised, maybe Adnan is me? Adnan is very close to my birthname and I love the meaning. Should I take this as a sign and take that name? It just feels right.

   I actually got my deed poll papers a few weeks ago, though I don't have permission from my mother to use them unless I take a gender neutral name or the nickname which I despise. I've spoken with her for a while about names, and she's only reacted positively once... How should I bring this up? I'm worried that she'll react negatively, for one because the name is new, and also because it's specifically masculine. I wouldn't use it formally until I've graduated my current school (I plan to go by a nickname or middle name for school once I come out officially). I also worry she won't like the fact that I found the name through a dream. I hate to make a fuss, and for some reason I was worried to even post this here.

  Any suggestions?

It is your name. You are the one that has to live with your choice. You can consider your mothers feelings but it is not her call. At the worst you might have to wait until you are of legal age to change it yourself. Eventually your mother will have to get on board or you can cut her out of your life. A guy I know has parents that are a few states away. He rarely visits them because they use the wrong name and he does not want to put up with the disrespect.

If you can't get the name you want til you're of age then I'd wait. It'll be worth it in the long run.