I'm a 20 year old student studying Graphic Design. I occasionally get clients who would like me to completely redo their website such as designing a custom theme, adding plugins and doing it all with wordpress.
Sounds like you are playing the role of the web designer and web developer in those situations. If you consider yourself very very good with UI UX design people are willing to pay big bucks for quality work there. As far as the development side it's more about the timeline for development and how many bells and whistles. I've worked with small to medium sized businesses and do not think $250/hr is unreasonable or unusual for top quality design and development on a normal timeline.
Happy to discuss more just wanted to get my thoughts out to bring a bit more perspective in.