I've always just fed them until they've had enough. I'm amazed that you're 11 month old is still letting you feed him, mine had all commandered the spoon by then and sent my butt packing! (That will get you worried about whether they're eating enough, "Did you get any of that in you, or is it all on the floor and in your hair?" It is such a good thing that they're still getting most of their nutition nutrition from breast or bottle until their 1!)
If he's eating lots and lots, he's probably burning it all off with his new mobility skills, and soon he'll be far to busy to want to stop to eat and you'll be wondering if he thinks he can live on air.
As long as he's staying on his percentile curve, don't stress, it's just more of them knowing their own bodies and what they need, regardless of what will let their mother sleep at night.
Make it fun, make it about learning that there are lots of lovely healthy things to put in our mouths that arn't dead bugs, and treasure in your heart that you once worried that he was eating too much for when he goes through the stage when food is a hugh bother.