Cardio and DIET are the two most important factors in seeing your abs. You can train abs relentlessly but will never see them if your Bodyfat% isn't low enough. Also, did you have a c-section with your kids? it's a bit harder to rebound from that since the ab wall gets cut. what are you currently doing for cardio? and do you know your bf%? sorry to ask so many q's but just tryin to get a feel for where we need to go...
~KITTY