I have a similar problem, I enter the mind-awake body-asleep state now with relative ease, but when I start feeling vibrations my heart starts pounding and breathing becomes labored. Perhaps just getting used to the vibrational feeling over a few attempts will ease the process.
News:
Welcome to the Astral Pulse 2.0!
If you're looking for your Journal, I've created a central sub forum for them here: https://www.astralpulse.com/forums/dream-and-projection-journals/