Vibrations Keep Dissapearing

Hello everyone, I have been having some troubles recently when trying to astral project (im quite new to meditation and projecting) where I start getting numb and tingly, finger tips get cold and the goose bump vibrations come in waves a little but then what happens, I can only describe it as if spirit swells a little bit around my physical body but then it settles right back into physical. I have tried focusing on the vibrations and it makes them last a little while (few seconds) and I have also tried ignoring them and when I do this they usually only come in a single wave and dissapear but I don't get the feeling of spirit "un-swelling" back into physical. Another problem I keep getting is once I feel myself drifting into the vibrational stage, my foot will twitch and it breaks the trance. Any tips on how to sustain the vibrations long enough to project would be appreciated, thanks!