for me it hasn't been so much a random ebb and flow as it is certain specific triggers that set it off, even now after living full time for 9 months. I'm really referring here more to the body dysphoria feelings than to any gender identity issues, because I have no doubt whatsoever of my female identity and that is never in question. But learning what those triggers are and how they've changed over time has helped me to deal with them. They are mostly all now related to the challenges of transitioning.
At first I simply tried to avoid the triggers, but in the real world that is not always possible and not really a permanent solution in any case. So now I just keep my goals in mind: my surgery, the life I plan after surgery, etc. That helps me to stay focused from the horrible distraction and emotional upheaval that dysphoria brings with it. For me transition does have an end, and that end is in sight once my surgery is complete.
I've learned it is better to face your challenges head on, in this case dysphoria, than to run from them because that just never works. Better to deal with the challenge on your own terms than the terms of the challenge itself, because it will always try to convince you it is insurmountable. Tell it No, it's not; face it down and show no fear. The way around it will often then present itself. But as long as you play the game of run and hide and deny, it only get's worse.