Not false but developing your country is more of a privilege of the rich than a reliable mean to achieve goals.
As mentioned, getting allies and having them to do the dirty work is much easier and lighter for your treasury. It looks that you have seven kids, that means seven potential alliances. Try to ally the strongest Maharajas. If you can find only one who is alone stronger that your liege, you are to go for the independence but ideally just betroth or marry all your kids to strong ruling families. Bertrothals are especially useful since you can just cancel them after a won war.
Touchè! I am not a pundit of the game yet and have so much to learn. Must be more cynical