First of all I am really glad that in general, you are feeling better and it just goes to show you that people can recover from depression and things can improve. Well done, you have done hugely well.
I would encourage you not to be hard on yourself - this is something I am nurturing in myself everyday. I feel as """depressives""" quote unquote/sensitive people prone to depression, sometimes we can make things worse by over analysing ourselves, and beating ourselves up (possibly due to depressive's low self esteem??). We can over analyse our moods and be self critical about them, when the reality is it is okay to not be okay 100% of the time, just so long as OVERALL things are on the upwards curve. Ironically, the being over self critical and bad self esteem is typical of depression, so in over critcising our recovery process we are again falling prey to the depression. It is good to be mindful of this please.
It is super easy to fall into the trap of depression, it is as if you become easily anxious that you are going to become ill again, just because you are on a low moment. And that thought, and that fear, can then be a slippery slope back down into depression. We MUST be hyper aware that our thoughts can often dictate what happens to us, in terms of leading you down the negative spiral. E.g. if you think oh no, am I doomed to be depressed again? oh no, oh no, then it is more likely to happen. I am not talking about people bringing depression on themselves here and blaming them but rather it is the nature of the illness that it perpetuates itself. But what happens if we can slowly teach our minds to recognise and observe our thoughts? This is the power of mindfulness. I used to think it was wishy washy bullshit, but practising it every day does make a difference. You can get better at it with time too, try the app: Waking Up. It is free and if you do it everyday, you should get more comfortable with being aware of your consciousness.
If you can recognise a thought, and the space around it, and say: okay, thank you for that thought, I am just going to observe the thought, and then send it back out there, surely there is hope.
Anyway, when you're on a low it is literally the HARDEST thing in the world, to think this is going to pass, and just because I am having a blip, it doesn't mean things aren't progressing, but in that moment, all you can think about is "I'm tired of this, I'm tired of life, let me out of it!!!"Your brain immediately buys into it, and in that moment, the pain feels like something that never lifts, even though it does. What if in that split second, we could somehow immediately say NO... this is just an off moment. It would be a game-changer.
"I'm feeling the best I've felt in decades for the most part, but I'm having what kind of feels like a traumatic experience or something. My mood drops to rock bottom in a couple seconds for a minute or two and I have severe suicidal urges. Then my mood goes up a fair amount over a few minutes and then slowly creeps back to normal after around an hour or two."
Now this quick mood changes thing over the period of minutes or hours is typical of the borderline personality disorder. I am NOT saying you have it, just that it is a symptom of it. I know from personal past experience that the quick extreme mood changes are very disturbing, and can become exhausting. It is definitely worth talking to your psychiatrist and psychologist about and your idea of a mood changes record is excellent. In any case, I really hope that my advice above about has been of some help to you, it is all I can offer in terms of wisdom right now. Remember we are human beings and we are allowed to experience a range of emotions, but if this feels unhealthy and scary you would be 100% right to seek help on it. I think you should really remember to give yourself more credit and a pat on the back more often about your recovery. Be kind to yourself in your thoughts, it may help you