That is really big for 1.5 years old! I call that "accelerated" growth. The photo below is also of an Eastern Hermann's tortoise that I have here that was born in August of 2008. It is currently about 2 1/8"-2 1/4".
LOL its good that hes a good eater, now just focus on the good stuff.. like i tell alot of my client i help with animal training its not liek they can go to the fridge and open it up.. Only YOU can prevent chubby pets! LOL
You bought your little one at the pet shop right? When I bought my Hermy they told me SHE was 10 months old, but when I showed the pic here on this forum, the experts told me HE was about 3-4 years old. So maybe he is not 1.5 years old?