i noticed if you feed smaller prey the snakes tend not to grow as fast i have an 06 albino female that 350grmas now and i have 06 females that are over 1200 grams. the albino only eats asf rats or mice and the others are eating rats and the albino just doesnt eat like the others do. i have babies that are around 4 months old that are over 200 grams easy so i would say your snake is a bit thin, but give how your feeding and what your feeding it would be about right.