Typography for mobile 720×1280

I have one question about typography for mobile screens that are for retina. Let’s say that the font size for a normal screen is 14~16px. How it is going to be for retina? We make it double and for normal text will be 32px font size.

What about the other font sizes for the headers? If I use an increment number to define the other sizes, it looks bad. See photo attached and let me know your suggestions!