I am currently 18, soon going to be 19, and I'm not sure if I am fully developed yet.
In the stage 5 section it says that I will be able to grow facial hair. Up until about a month ago, I was able to grow facial hair on most parts of my face with a few spots in which there would be no hair. i.e., I would be able to grow side burns and a goatee if I wanted, but not a full mustache or a full beard. Like I said previously, these spots without hair are gradually getting more hair.
My voice isn't consistently deep, meaning there will be some days that my voice is really deep like my dad's and the other days my voice would be fairly high. I don't know if my voice is meant to be high or what.
Also I think I might be a little bit of a late bloomer. When everyones' voices were changing when I was in junior high, my voice was ridiculously high. My voice finally started to get deeper that summer and throughout high school.
As for my genital area, I haven't made any measurements or anything but the hair seems to be all there. Throughout junior high and high school the body hair has never been an issue for me. I might not have as much as some guys, but it all seems to be there.
Any feedback is greatly appreciated.
In regards to facial hair, most guys cannot grow a full beard until a few years after they reach stage 5. What you are seeing is perfectly normal.
Your voice will get more consistent over the next year or so. Your brain simply is still trying to figure out how to manage your longer vocal cords. It takes a while. If you are hitting low tones, then your voice will eventually settle into that range.
To be in stage 4 at 18 is a bit later than most guys, but it is not out of the range of normal. And it does sound like you are either at the edge of stage five or just starting stage 5.