Too much food for 12 month old?

Okay so, I've been struggling with whether I feed my 12 month old too much or too little. He loves food and is generally a good eater. We've just gotten him down to 1 bottle of formula a day recently. We kind of ripped the band-aid on that and he is doing really well and not acting like he cares that we've taken most of the bottle s away. Anyways, one thing I've noticed with him is whenever I give him a sandwich of some kind he will eat the whole thing. I started out with giving him a half but like I said I worry he wasn't eating enough especially because I struggle with finding good meals 3 times a day lol...so I worked up to a whole sandwich with the crust cut out...is this too much? He gets fruits usually with it...and now whole milk. I tend to wait for him to tell me when he's done...I don't want to over feed him though...