Here are a few simple ways to get more out of the tube
Place the tube in both of your hands. One hand at the top, one at the bottom
Starting at the bottom end of the tube, run it over the edge of a bench until you reach the top.
This should push all the toothpaste to the top of the tube.
Once you can't get any more from the tube after completing the above, cut the top of the tube off.
Dig your toothbrush in. There might be another couple of portions left.
Keep squeezing the toothpaste to the top of the tube every few days. The squeezers and twisters in the family will see that there is more toothpaste to use. If you leave it until the tube has been twisted to billyo, they'll just throw it in the bin when you are not looking,