babysitting raise?

Hi, I am a babysitter in Lexington, I work for about 3 hours every morning mon-Thursdays almost every week! They pay me 15/hr for just one baby-1 1/2 yrs. I have drove from Richmond to here about every morning and they started paying me for drive back in January I think, 15 a day on top of my hourly. I am moving to Lexington this semester. Should I be charging more like 18 an hour. Or is 15 a fair price. And also they are more than able to pay it but it’s not really about if they can it’s just about what is right and fair.