Authors Note:
I know you hate these, but I just want to clear something up.
Bella is 17
Ok here is the confusing part
Jacob was turned into a werewolf at 19
When he was changing he had a major growth spurt and could pass as 25
He found Bella at 19 (she was a baby, like 3 months old) and 17 years later he looks the same. 19 + 17 = 36 , so he is really 36 but looks younger b/c he is frozen in time
I hope this is all cleared up and that it did not cause much confusion:)