Honestly I dont have any, I do lots of research before purchase...
Depending on the age, they should only eat around 5 crickets max so I hear, so yours definitly sounds underfed....
It is possible it is still in winter dormantcy, some leos do it even with proper temperatures it seems. So it might eat less, of course this is a problem if it is looking thin.
There are some supplements pet stores sell for feeders, try giving them those, they have nutritious supplements for the pets. There are some recipes on the chameleon forum for gutloading, try those, but they require some strange ingredients.
Also remember to coat your feeders in calcium supplements (very important for leos)