energy bar expanding to the right

I'm attempting to create an energy bar for lack of a better description (it actually has a different use, but I'll spare the details).

Essentially, it's a bar (T2DSceneObject) that increases in size starting from the left and expanding out to the right.

Here's my problem:

Right now, when I change the .Size property, it resizes from the middle and expands the left and right equally.

Now the normal calculation to fix this would be the following:
increase the size by "factor"
change the X property: current x + factor/2

The problem is that the x property is measured in different units than the size property. i.e. a value of 1 size does not equal a value of 1 x-position.

Any ideas of how I could accomplish this?

Thanks!