Unfortunately, I don't have links to good books or online references, but I can describe some of the tactics that I (as a tenured faculty and low-ranking university admin) use to deal with these issues. None of them works perfectly, but they work better than what I used to do - and what you also seem to do (have a big list of "stuff" that needs to be handled, pick every day what to work on, and get increasingly more frustrated that the list grows rather than shrinks).
Rigorously use your calendar as a time planning tool
My Outlook calendar is the front and center of my time planning. I have meetings in there (obviously), but I also reserve time blocks for all non-trivial tasks I have to work on. I map these out days, sometimes weeks or even months, ahead of time, so that every day when I get to work I have a clear idea what I will do that work day. I generally strive that all tasks in my TODO list that have some specific deadline also have a reservation in my calendar when I will do them.
Of course this works better for more concrete, short-term work ("do XYZ review") than ongoing research, but even there I try to break it down into meaningful TODOs and I schedule them. Even if I can't break down a research project into specific TODOs yet, I still create a TODO that essentially boils down to "think about project X". Like you, I need significant uninterrupted time to do anything meaningful, and this tactic allows me to schedule things in a way that I have enough consecutive time to make progress.
This also helps my anxiety a lot - I find it easier to fully dedicate my mental energy on work on project X knowing that there is specific time reserved to work on project Y, and it's ok if I don't think about Y at all this week. Further, this way I am able to give more concrete estimates to students or staff when they need something from me, since I will schedule their task in my calendar and have an idea when I can realistically get to it.
Re-Planning is Normal (but needs to be done consistently)
Of course your initial plan will often not work out. Sometimes short-term tasks that come in need to be prioritized over what you initially wanted to do, and sometimes things just take longer than anticipated (though I usually reserve conservative time blocks to make this not likely). This is fine, even expected, but you should adapt your planning religiously whenever it happens - move all blocks you had to skip today to somewhere else in your time plan, potentially moving other blocks around as required to make all deadlines meet. This sounds tedious, but is really not a big deal most of the time.
The most important thing is to not get into a habit of planning and then just silently doing other stuff instead. Once you get to that point your time plan essentially becomes a waste of time.
Prune Your TODO List (and learn to say no)
Once you start mapping out when you do which tasks, it might turn out that there simply isn't enough time to do everything, at least not yourself, in high quality, and on time. As a manager, part of your job is also to delegate some tasks - and this will include tasks that you yourself could do faster or better than the person you delegate it to. Further, not everything that needs to be done needs to be done well - sometimes it's simply better to do a half-assed job at something unimportant (and get it off your TODO list) than to never do it at all.
Finally, some tasks simply need to be pruned. In addition to my actual TODO list (the tasks I plan to do in the next days or weeks, and have reserved time for) I also have a "backburner" list where I keep all the things I wanted to do eventually but never quite found the time. It feels better to me to say I move a project to the backburner than to delete it entirely, even if quite frankly tasks rarely make it back from the backburner to the "actually do" TODO list. In any case, I try to keep my actual TODO list tidy and only containing things I know I will eventually (have to) do.
Similar to the time planning, I feel it defeats the purpose of a TODO list if it routinely contains stuff that you, deep in your heart, know you are never going to actually do. At that point it stops being a useful tool for time management and just becomes a daily reminder for you telling you how far behind you are and where you have dropped the ball.
Going forward, your schedule based time planning also allows you to assess if you actually have time for a specific task - and to say no if you can already tell that you won't have time to contribute to a project, do a review, or serve in a committee. That's another thing one needs to learn as a manager - you simply won't have time to do everything that sounds interesting or important, sometimes you just have to say no. Your time plan should help you decide when these times are.
Tools
I don't use a lot of high tech for this workflow - my Outlook calendar for time planning and Trello to manage my TODO list. Some people have suggested that a pen-and-paper based solution works better for them, but to me the ease with which you can re-plan and move things around in a digital tool is way too important.
Some parting remarks
That all being said, I believe part of your problem may be that your expectation of having hours and hours of uninterrupted thinking time and loads of time to progress your personal projects may simply not be consistent anymore with your position. Even the best time planning cannot create time out of thin air, and you may find that you simply have to scale back some of your personal projects to make time to adequately handle your management responsibilities and supervise your students.
This may initially feel difficult and unfulfilling, but in my experience this feeling is fleeting - after not too much time, one learns to generate job satisfaction from helping others achieve their goals (even at the expense of not being able to fully focus on research yourself anymore).
