size of a borneo blood

Snakes can be grown quickly or slowly, That is whats SO cool about them..Your snake hasn't suffered any detriment by such..As a breeder of Borneos I can have them at 3 plus feet and 8 lbs by 18 months or I can maintain them into the next year with only a small amount of growth..The pictured animal leaves some question as If its a borneo or a northern occurring Curtus/sumatran..

From that picture, the proportions don't look bad, so I'd say that either it's just a slow grower in the length department or the pet store doesn't know what they're doing by not feeding enough and slowing down the growth, or they told you the wrong age.