Anna,
I had a mate here on the weekend & we were having a few of my All Grain beers which he was wrapped with (first try)
I handed him a bag of Hop flowers for a sniff, usual responce "wow they are strong" (Galaxy flowers 15%AA)
After a few more mouthfulls of beer he said,
"Now I can notice the Hops in the beer, I never new what that was until now"
My guess is that it is the flavour or aroma Hops you can pick up in the Commercial beers, std can kits primarily deliver bittering only, by way of thier production.
I suggest you try adding some hops as mentioned by the others above.
boil about 15g for 15 Mins & add another 15g at flame out, use this mixture as you would your normal kettle full of hot water when you mix the sugar & concentrate in the bottom of the fermentor. (the hops should be in a mesh bag, they go in the fermentor too!)
For my kit beers, I do this in the normal household kettle (but not the one my wife uses for her Coffee)
Cheers, Mick.