Welcome to the forum.
It does sound as though you are in a difficult situation and that it would be sensible to move the sensor to at least the outside (or inside) of the arm to avoid lying on it.
If I sit up with my hand on my knee my sensor is on the outside of my arm, so I only lean on it in bed when I roll over onto my left side.
I don't think there should be any problem moving it even further round towards the front of your arm, although directly over the bicep might be an issue.
Others in this forum have worn a sensor on the chest or leg with success, but I can't really comment because I have never tried it.