your style will change. What I've always loved about your work is your character concepts. A lot of the characters you do would make great costumes/cosplay's or could be used for movies as a basis of how fantasy could still look credible in the real world.
I put no , that the stiffness is part of your style , but honestly thought you used a tablet! since you don't however , a tablet would make moves / strokes more fluid for you , but from my own personal experience with tablets ( I have 2 ) they're a bit weird and take a bit of getting used to
as for being " by the book " art is art , regardless of form , there is no such thing as " by the book " when it comes to inspiration
The drawings you do most of the time are pinups, and the art style you use has a tendency to look a bit stiff, it isn't you so much as the style I think. Sure you could make them more alive or fluid with a bunch of effort, but unless you are portraying the characters in a specific setting or scene the images of this style will look like that most of the time. I think you do a decent job at giving your subjects life, but if you want to make them less stiff try imagining them in a dire or pleasant situation. You could draw the setting and subjects around the main figure in action, though it will save you time to just draw the character. I would love to see you go more fully detailed images like [link] and [link] but only [link] has both the detail and feeling the character is really alive.
If you are truly interested in more flow, I would like to see the artwork you are producing on a regular basis turn into the next image. In my opinion nothing beats This.
What is it that you wouldn't like as a full time job?
I'm glad you enjoy doing this, and I hope you are offered some sort of work once in a while for it (even if you don't take it). You do great stuff, but I'm not going to say I don't care about you anymore because you won't push yourself further. That's for the selfish. You've already given many people on DA lots with your "free time," and I don't expect anything but that you enjoy yourself with what you do.