This is good book on learning in software dev, https://www.amazon.com/Adaptive-Software-Development-Collabo...

Make sure you get a title and compensation change that is proportional to the additional responsibility and increased value being delivered to the company. You may be surprised how that will change the nature and quantity of demands being made on your time.

If you keep saying yes (to everything you did before) and yes (to everything you are discovering you can do), it is only human nature for individual requests to increase to the point where they collectively overwhelm you. You could individually re-negotiate boundaries and committments, but that itself is work and requires political skills. A public change in title and a financial change in compensation will require executive approval and that process will help change company-wide perception of what tasks are the best use of your time.

Once that is out of the way (increasing your price as a form of demand/flow control), find good books and external mentors on:

  Leadership (managing down _and_ up) [1]
  Project Management (execution logistics) [2][3]
  Communication & Politics & Sales (human semantics)

[1] Being a Manager is lonely, https://news.ycombinator.com/item?id=8881752

[2] How to run successful projects (3rd Ed), http://www.amazon.com/How-Run-Successful-Projects-III/dp/020...

[3] Adaptive Software Development, http://www.amazon.com/Adaptive-Software-Development-Collabor...