Sirenz,
Just keep cutting then up in small pieces. I used to cut them in different shapes just for the fun of it. He will get the idea one day and then you will have trouble keeping up. My grandson went from things being cut up small, shoving in as much as could fit, and asking for the next mouthful, then a go slow, took forever to eat a sandwich, and now having a go at feeding himself. They get there in their own sweet time even though its a frustrating time for you. Hang in there and wait for the next stage to come along.