Ok so I wasn't sure where to put this thread. The 'transitioning' section seemed the best place but correct me if not. I'm new to the forums

So I'm 15, MTF transgender. I have had a lot of time to come to terms with who I am and I think I'm at an ideal point to start thinking about transitioning. Obviously, I'm limited until I turn 18 but living as a male is horrible for me. I feel uncomfortable all the time. I'm sure y'all can understand!
I'm thinking about starting to grow my hair out. I used to have nice, long hair but I cut it all off not that long ago in some attempt to 'fit in'. Mind you, it didn't look great before anyway. Now, I have a undercut, quiff style thing. Where it's longer on top, y'know? Don't get me wrong, nice haircut! But, for me... nope. My hair has a wave to it, I wouldn't go as far as wavy but its not straight, that's for sure. Ultimately, I want to grow my hair down to neck length into a sort of wavy bob and grow it longer when I feel like it.
My question is, what would you advise I do? Grow out the undercut and trim when I need to OR just cut my hair really short so I can grow it out better. I would feel uncomfortable for a while doing that but my hair grows SO FAST anyway. I want to part my hair towards either side eventually and that's difficult in the style it is now.
Talk to my hairdresser? Hmm, maybe. Not completely comfortable with doing so. What do you think? Any kind of advice about hair would be appreciated.