i would have thought you are going to have a discussion with yourself or the people who own the other shares of the business to work out whether you want a share of the business or a proper wage, It might be difficult to have both, it sounds like the business is either reinvesting, paying off debt or not very profitable if its one of the first 2 options you are probably lucky to have 20%, if its unprofitable for the sake of your future family you are probably under pricing your labour