While we have seen some somewhat "miracle" situations with men who have more than doubled their baseline Testosterone on their own, these are almost always with men who were very overweight & lost it while also reducing their alcohol intake (which was high). As someone who is not currently overweight, sounds like they practice healthy lifestyle choices, and despite making worse choices lately still likely with better habits than most men - It is likely you wouldn't see that kind of dramatic shift.

For your age, the previous tests, and your current test; you do sound like a pretty typical low Testosterone patient who is genetically disposed to have low T at this timeline due to aging in his life. This is how it tends to onset as well. Once your T reaches a certain personal low threshold, many processes that promote Testosterone production are hindered & create a negative feedback loop. That sounds like what you've experienced with that massive drop.

Let us say though, that you were able to revert to your previous levels - All Testosterone goes down with age. You will almost certainly hit the exact same situation in the future sometime soon if you are so close to that "break point".

That's an opinion from just what you've said, though. However we too would feel you're a classic low T case.