Are my Abdominal exercises working?

I've been doing Abdominal exercises for a fair while now (And before i get someone saying about it, no I'm not just doing crunches, crunches and more crunches. I do vary the type of exercises I do for my Abs) All I want to know is how do I know if the exercises are working or not? I have noticed change in the fact that I now have a kind of bump or ridge where my Abs are but not clearly visible 'packs'. Does this mean I have too much fat that there not showing/ starting to show? Or is it just an early stage before the Abs fully show? Any help would be appreciated :)