
Barry Oshry is one author that has investigated and detailed organizational behavior and developed simplified models that can provide insight and guidance for daily practice and planning. He has multiple books available, I recommend "Seeing Systems". Here's a video recording of a talk covering some of the content: https://www.youtube.com/watch?v=VYpO-pK7IFA
It give insights a) on why this happens and b) what scope for action you have (a lot).
ad b) i recommend two sided strategy> continue to do your best work while not caring about it. - and - start "beening open for new oportunities" side project job hunting & networking. it might cost some energy, but either the situation in your job improves and you can keep your job, and if not, you have a head start when your job hunting gets serious.
Read: Barry Oshry - Seeing Systems https://www.goodreads.com/book/show/1241559.Seeing_Systems
b) >I was hired for a position that has no decision making power at all. Power isn't given, power is taken. Trust is earned. Leadership = Power * Trust
but if a) is your current view, you can forget b) especially the trust part. if a) is true, then change the company, best start your own.
2nd Article "Leverage Points" http://www.donellameadows.org/archives/leverage-points-place...
after these two you will have enough know-how on how to identify and manage systems (i.e.: your growing company)
then the only thing between you and success is reality, for how to influence the company reality you live in please read
3rd "Seeing Systems" http://www.amazon.com/Seeing-Systems-Unlocking-Mysteries-Org...
good luck and have fun (with the books, with your new responsibilities)