One nerdy already gave you the footbed info above, so I wont bother adding to that, but what I wanted to add was checking the volume and shape of the heel of the boot and also checking the space above the instep.
Its important to make sure the heel pocket fits you. All heels are different shapes but there are only so many boot shapes, so it will be quite common to need to change the shape.
Remember that a heel lift, however small will change your balance point. This could be good for you or it could be bad.
What could help some people more is padding the top of the liner on the instep. Adding foam to the heel of the liner can help, but its often a good idea to put extra foam in front of the foot rather then behind. Its for this reason padding the instep may help. However if there is not much space here this may not work as well as adding the foam to the back of the liner.
But hopefully this shows there is much more going on then just your heel lifting. A good bootfitter can help you really dial in and help you get the most out of your boots.