No problem! That was something I always worried about too when I first had my son, because I didn't want to over feed him, but normally they will stop when they are full and they will let you know what they need. Just trust your instincts, you are his mom so you know what's best for him! :)
In my opinion, yes. I have always given my son as much or as little as he wanted to eat. I never forced more on him or gave him less, and he is completely healthy and it has always worked really well for us. When the babies are going through a growth spurt they eat ALOT.