Turner syndrome. Turners syndrome is one of the most common reasons for premature ovarian failure. Many turner syndrome patients will never menstrate because of rapid follicular depletion. Since you have a mosaic pattern, it is unpredictable when your ovaries will fail. You could potentially start menstruating and start ovulating for a few years before ovarian failure.
Possibly. Mosaic turner's means that you may or may not have certain features of turner's syndrome. If you're 46 years-old, however, normal menopause can start at this age also.