Washing my hair every day

So my mom keeps yelling at me for washing my hair every day, but if I don't wash my hair that often it'll get really greasy and overall just gross. I've told her this before, plus I've tried refraining from washing my hair for a while (a day or two) then washing it ("hair training"), changing out/cleaning pillowcases often, and still to no avail. It's getting to the point where I need to hide my hair from my mom when I wash it. Thoughts?