GAAAHHH DAMN I TYPED A LONG-ASS REPLY AND THE BROWSER CRAS--- oh nvm there's autosave whewwwww

Oh wow that's awesome!! congratulations on the lucid and confronting the nightmare

You know, i forgot to mention this before but even *intending* and thinking about facing your nightmare helps you a lot to actually do it. It's pretty much mental conditioning. So great job!

As for the WBTB dilemma, have you tried experimenting with the time you sleep as well as the time you stay up? Those times you had to wake up early, it could be that they coincided with your REM period, so the WBTB was much more effective. The key to WBTB lies in knowing YOUR optimum time, and not relying on what others say it should be. I suggest keeping logs of the amount of time you sleep and the amount of time you stay up for your WBTBs, including the conditions like if you had bright lights when you woke up or if you did or ate anything prior or during the WBTB. All of those affect how it's gonna work out. I gotta be honest, it took me quite some time to figure out my optimum time. (My time is around 2 hours of staying awake and about 4 hours of initial sleep). But i tell you, once you finally figure it out, it's all worth it! Provided ofc that you dont have any dramatic changes in sleep schedule.

The thing is, it's hard to pin down exactly how WBTB works. Sometimes it's just placebo effect, sometimes just luck. That's why I recommend experimenting with it as much as you can because personally it makes you more confident about yourself when you actually know what you're doing as opposed to just "hoping it works this time".

Oh and another thing, REM rebound.

REM-rebound happens when someone is deprived of REM sleep, therefore, they usually occur much more quickly and last longer in order to make up for the lost time.
That could be another possibilty. If you got only very light sleep and few hours, your REM could've had a boost the moment you slept again, making you lucid quicker.

Cheers!