Your experience as I see it was not so much close to a WILD,
Steph, but an actual successful WILD dive...with one small exception.
It seems that you managed to fall asleep while maintaining awareness (the WILD part), but there was no dream "waiting" for you -- in other words, you were in NREM, or
delta sleep.
Much of what you describe above sounds remarkably like many of my excursions into delta. So there is a chance that you did everything right, but your body simply wasn't in its REM period yet. Trying to form a dream without the presence of REM can indeed yield the results that you got.
I think that "startle" reaction you kept getting was probably pretty normal too, because your mind was in a truly novel place, and focusing on it might have required too much of the stuff that wakes you up.
How to avoid this? Patience. If you're having trouble finding your dream, or are encountering odd phenomena like you did, simply assure yourself that it will pass and your dream will eventually form (or, perhaps, your dreaming mind will eventually permit you to form a dream). In other words, think of events like this for now* as just more noise, and ignore them. By ignoring them, you should reduce the overreaction you experienced and be able to hold your focus until the dream actually starts.
* Note that I said "for now," above. That's because later, when WILD is second nature to you, you might find delta sleep an interesting condition to explore and enjoy. For now it might be an obstacle, but later it might be something very, very interesting!
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