"Mass" is the amount of matter that makes up your body. It doesn't depend on where you happen to be, any more than the amount of money in your pocket depends on where you are. If your mass is 65 kg in your kitchen, then it's 65 kg. Doesn't matter whether you're in the basement, in school, at the bottom of the ocean, in Mexico, in China, anywhere else on Earth, anywhere on the moon, or floating in space.
