I did just about the same thing , going on three years ago. With a twist.
I had advocated for the creation of the team I had led. For quite a while I made an absolute pest of myself about creating a team of engineers with a specific purpose. THis meant I wasnt just leading a team of QA, but rather a mixed team of engineers and QA.
To make the transition interesting, my team was largely made up of engineers I had been working with as peers with a couple new hires mixed in.
The smartest thing my company did was to bring in a consultant to conduct a week long seminar on making that very transition for a dozen of us new to the leadership game. First it gave me a peer group to discuss challenges with long after the seminar. Second it outlined the change in my work. Third it outlined common pitfalls and mistakes. Which allowed me to honestly examine my progress and make corrections as needed.
One thing I can say is that"Imposter Syndrome" will sneak up and mug you at the least expected moments. I had to convince myself, especially when I had a set back, that I belonged in the role. It was a learning process and a skill that would take time to refine. Peers and my own manager helped with this a great deal.
It took time to evolve a working arrangement with my team. I was honest with them about the challenges I had about making the transition and sought their help in doing so. As I established myself as an advocate for them as people and engineers, it paved the way for this arrangement. It took events like showing I was open to feedback, but that I would make decisions; while talking responsibility for those decisions; to help establish this relationship. I would do things like keep them out of unnecessary meetings, including them when their expertise was necessary, but otherwise not clouding their schedule with planning and cruft they didnt need. Engineers love that.
Your job, oveer time, is less about you getting “work” done and more about managing. your team as humans and engineers. your team’s interface with the organization as a whole. Negotiating. solving problems.
There are many good resources out there. But I think the most valuable is an internal company peer group of managers to help you make that transition.
Im kind of beginning to ramble. So Im going to slow up there 
EDIT: PS: I just encountered this quote and I find it relevant to my experience.
Colin Powell said “The day soldiers stop bringing you their problems is the day you have stopped leading them. They have either lost confidence that you can help or concluded you do not care. Either case is a failure of leadership."
