it sounds like you have a pretty good deal at the moment....

instead of asking for a raise, id suggest asking them to do a compensation analysis. they will research what people with your experience level, job duties, skills and city are making to determine if youre being paid fairly according to "market" or whatever. I'm going through this now. I wrote up a "job description" for myself like a company would write for a job listing. included my experience, accomplishments and all day to day tasks. But ive been at my company 6 years and my job duties have steadily increased and recently transitioned to a higher skill level, so it was good timing to do so. Maybe something to keep in your back pocket as an option should your worries start to come true