Using Javascript to roll over a progress bar from right to left

so i have this progress bar which works fine from left to right. Though i'm trying to make it work from right to left instead. I've tried making the last attribute the parent, and then traverse back, but it wouldn't work.

$(document).ready(function(){
  
  var current_fs, next_fs, previous_fs; //fieldsets
  var opacity;
  var current = 1;
  var steps = $("fieldset").length;
  
  setProgressBar(current);
  
  $(".next").click(function(){
  
  current_fs = $(this).parent();
  next_fs = $(this).parent().next();
  // var next_fs = $("#progressbar li:last").prev("li")


  
  //Add Class Active
  $("#progressbar li").eq($("fieldset").index(next_fs)).addClass("active");
  
  //show the next fieldset
  next_fs.show();
  //hide the current fieldset with style
  current_fs.animate({opacity: 0}, {
  step: function(now) {
  // for making fielset appear animation
  opacity = 1 - now;
  
  current_fs.css({
  'display': 'none',
  'position': 'relative'
  });
  next_fs.css({'opacity': opacity});
  },
  duration: 500
  });
  setProgressBar(++current);
  });


  

  $(".previous").click(function(){
  
  current_fs = $(this).parent();
  previous_fs = $(this).parent().prev();
  
  //Remove class active
  // $("#progressbar li").eq($("fieldset").index(current_fs)).removeClass("active");
  $("#progressbar li").eq($("fieldset").index(current_fs)).removeClass("active");

  
  //show the previous fieldset
  previous_fs.show();
  
  //hide the current fieldset with style
  current_fs.animate({opacity: 0}, {
  step: function(now) {
  // for making fielset appear animation
  opacity = 1 - now;
  
  current_fs.css({
  'display': 'none',
  'position': 'relative'
  });
  previous_fs.css({'opacity': opacity});
  },
  duration: 500
  });
  setProgressBar(--current);
  });
  
  function setProgressBar(curStep){
  var percent = parseFloat(100 / steps) * curStep;
  percent = percent.toFixed();
  $(".progress-bar")
  .css("width",percent+"%")
  }
  
  $(".submit").click(function(){
  return false;
  })
  
  });

above is the script i'm using, which rather than going from RTL = 1 2 3 4, goes RTL 1 3 2 and stops and doesn't reach four

i've also attached a fiddle with all the code https://jsfiddle.net/s327e1uo/1/

Thank you