I don’t have anything specific to say about wording, but I will comment about the coming out process.
It’s a good thing that you want to initiate the conversation. That way it insures that you get to say what you need to say. Put some conscious thought into what you want to/need to say and even write your thoughts down. It will help to crystalize what you are thinking, but I would caution against using it as a script when you have the conversation. It comes off better if you are talking, looking at the other person (in this case, your mother), reading body language, etc. I think it also helps to say your piece uninterrupted as the flow and continuity would likely be better. Above all, what you are conveying are your innermost thoughts; things that have been rolling around in your mind for a long time. It is useful to think in terms of a chronology. Things such as when you first had the thought that there was something different about you. I suspect there were other points or events through your life that continued to inform your sense of gender identity. Writing it down can help get the chronology right.
We don’t sit down to breakfast one morning and in the middle of our corn flakes think “Oh, I’m transgender.” and continue eating. It is a process. We have thoughts that we don’t feel or react similarly to our peers or we might like different things; for example, trucks instead of dolls when we are children. We have thoughts and while we might suppress them, they will come back and sneak into our consciousness. As this back and forth continues, it may eventually lead us to a crossroads where we really have to come face to face with what is going on and try to deal with it in some fashion.
Many here have chosen to work with a therapist in order to provide some insight as to what is going on and to maintain focus on the important topics. They won’t solve your issues for you, but they can help you think about things in a useful and constructive manner. But, and this is important, the therapist needs to have experience in working with patients having gender issues as everyone does not have this focus.
I also suggest that you do some searching around for transgender resources. You live in a major metropolitan area, so there should be support groups, counseling resources, etc. available.
I encourage you to complete your Profile page. It helps other members get to know you better. The page is always available and can be updated at any time.
If you would like to search for other members in your area, click on Social in the menu and then Member Directory…