i had a problem like this with my largest corn, he isnt fully grown and i am new to introducing larger items to him as he was my first snake, so i just guess what he should be eating by his weight and by the size of the prey next to his body (with the munson plan as a guideline). although i did feed him double fuzzies for a bit longer then i should of and when he moved up to 1 small mouse he only had to eat 3 and then was big enough to take 2 small mice at a time. i guess its better to keep them on a smaller prey item if your not sure, instead of trying to feed them something that is to big for them