This Is Then End

Well, you're definitely not alone. I've come across many people who've experienced similar phenomena, and I experience it myself.

Here's a thread from Dharma Overground of experienced meditators talking about it.

Some things that have been of some help to me are to imagine breathing out of my feet (or some other innocuous part of the body), or closing my eyes and realising that the sensation itself doesn't tell you how big it is or what its boundaries are. These are added to the sensation by thought.

Also, remember that you can feel pain in a dream and be quite disturbed by it, only to wake up and realise it was only consciousness, nothing more. You could try applying this to meditation. In 'reality' or in dreams, the consciousness is self-evident, but the content of consciousness can be highly dubious. I'm told that lucid dreaming can be achieved by keeping one's attention on the context (consciousness) instead of on the content (phenomenal objects). I find the same to be true of the 'waking dream'.

Lastly, even science will tell you that you're more than 99.99% empty space. We feel so very solid when we look at the body how we're accustomed to looking at it, but this is because we're ignoring 99.99% of what's 'there' and fixating on the less than 0.01%. Try placing your attention on all that empty space! Feel how much room there is within the sensation, how spread out and sparse it is. Imagine it from the subatomic level. How does it feel then? The sensation might be similar to the tiny white stars in a black night sky.