Do my own hormones make me fat?

Sure. We will use polycystic ovary syndrome in women for example. Though the mechanism is not known for sure, women with pco have elevated androgen levels. These women tend to be Insulin resistant & do not metabolize carbohydrates as well leading to weight gain. It's complicated, but all interrelated to hormone balance.
Depends. Depends on which hormone but too much of certain hormone (cortisol, insulin...) can make you gain weight, regardless of whether it's from the outside or your own hormone.