You can see yourself so well by regular mirror because the mirror can reflect the visible wavelengths of light very well, and your eye is sensitive to this range of wavelengths (400-700 nanometers).

Had you tried to use a mirror to reflect much smaller wavelengths such as X-rays for example (about 0.15 nanometer)? You would not to see it very well, even with an instrument that can detect such wavelengths.

Even in the mirror some of the light intensity (about 5%) is not reflected but normally you don't feel this.