Miles Allan:
... My consciousness then folded into this awareness that I was either completely present with sensory experience or I was lost in thought. What was unique to my consciousness at this time was that there was clear viewing of being lost and identified in thought.
...I also began worrying because I had to work that evening (I work as a paramedic, a job where I didn't believe my newfound awareness would serve me or my patients e.g. persion is dying. If I did nothing, it would be as equally good/bad as helping them). My concern at the time was that if I'm mindful in this way, then I wouldn't experience good or bad again...
What was this experience? Was this experience a glimpse of 'Anatta' or being 'Unborn' as J Golstein says?
How should I process this experience? are my doubts/concerns valid?
Where do I go from here? Should I be focussing my meditation practice in a way to replicate this experience?
These are all good questions -- probably familiar to a lot of us with long-term meditation practice -- and I'm glad you choose to ask because it's the kind of thing that can needlessly worry someone.
Here's kind of a long answer, but I think it will help...
When we are growing up, sometime around age 4 or so, we start talking to ourselves. ALL THE TIME. If you listen to kids, at a certain point they start narrating their life "I put this block here. The doll goes here. I go get the crayon..." As you are watching the kid, you might be tempted to say "you don't need to say everything you are doing. Just do it."

But it's part of developing the verbal mind.
The weird thing is that this odd behavior becomes so ingrained and pervasive in adults --- it becomes the verbally thinking mind. And 99% of adults are so identified with the verbal mind that they think that is what I am. I am my thoughts.
Meditation is usually the first time an adult starts seeing the verbal mind as just another phenomonon of the body-mind. Like you said, you can acutally "watch" the mind be tumbling around in thought. Sometimes people call this "glimpsing the mindstream". The interesting thing about this state is you can't really "think" about what you are seeing, because that would be more thoughts, but the witnessing/awareness aspect of the mind can start to see thoughts as thoughts.
This can be shocking, but thoughts have always been thoughts, sensations have always been sensations. Without meditation, there really isn't much nuance in peoples mind. But the more you observe and understand your own mind, you will see how experience is made of a lot of component experiences subtle sensations, sensations, urges, subtle emotions, emotions, proto-thoughts, one-word thoughts, and full sentence thoughts... It will be obvious that experience always was this way, but you just didn't see it before.
There can be a crisis of confidence that "if I see my thoughts as thoughts they are unreal and will go away, leaving me without thoughts" That's not really true. There might be an adjustment period when you are thinking less and less compulsively, but it is more like you arrive at a new healthy balance for urges, emotions, and thoughts. Usually this is a lot less, a lot more calmer, a lot more "clear", than your life pre-mediation... but they don't really go away completely.
The last thing you will see is that "good/bad" is actually a full body experience. We might initially think "I need my thoughts to figure out good and bad", but really it's something that is part of every aspect of experience. It's actually very common to start navigating life more morally and responsibily by tuning into the "felt" sensation of the world. In other words, feelings and emotions can actually be more accurite than clunky word-thoughts for moment by moment navigation.
(Notice that you mostly don't "verbally think" how to catheritize a vein. By now you probably look and "feel" like a nice straight surficial vein would make a good target. Your body knows that the "sensation" of having a relaxed but calm hand sensations means you are ready to start the needle moving. You "feel" for the pop, you "notice" the flash, you withdraw the needle along the path of least resistance, you feel the right pressure under your thumb which stops the blood as you tug off the tourniquet, you know in your gut if you have a patent IV, but you hook up the line and then see, and you watch your feelings as part of deciding are they getting a good flow...)
It's true that we all talk to ourselves while doing job stuff... but it's also true that the real skill shows up in a non-verbal way. It's just we don't notice it very often.
So basically, you are starting to "see" thoughts. You could say you are seeing the not-self aspect of thoughts and are starting to identify with awareness more than the content of awareness.
A big trap at this stage is thinking "oh I'm awareness. and when I'm awareness everything is nice and no problem... therefore contents of mind are the problem!" NO no no!

Contents of mind are just fine, no problem. The point is to learn to see everything as it is. See sensations as sensations, urges as urges, emotions as emotions, thoughts as thoughts, states as states. You don't need to do this verbally (e.g. labelling everything with words) but it can be good practice at first, like the 4 year old that learns to label their actions. A meditator learns to label their inner experience. But ultimately, you can just "notice" rather than note, like you did on your 30minute walk home.
So good job! Sounds like you are seeing your own experience more clearly. No need to panic or push practice into one direction or another, just continue to explore and ask questions. Slow down if it is too intense, go on retreats when it seems right, etc.
One thing I will caution: it's almost ALWAYS the case that we get a "glimpse" of new stuff and then it takes days, weeks, months before another glimpse. That's just normal, it doesn't mean anything is wrong. Also, the mature version of what we glimpse is usually less extreme/profound over time... it becomes kind of normal. So be on the lookout for trying to make experiences into "very special things that show how very special I am"

Of course, it's totally okay to get excited about new developments in our practice, but just don't buy into the hype about different spiritual states.
It sounds like you are getting to stages where having a teacher and sangha would be helpful --- I highly recommend establishing a support group of some sort. (DhO can be kinda random, not necessarily dependable.)
Hope this helps in some way!