What is the interaction between Thunderwave and being required to target your own space? [duplicate]

The spell Thunderwave has the rather unusual target area of a 15-foot cube, the point of origin for which is the caster, which is generally understood to mean you can either position the cube anywhere adjacent to yourself, or (for whichever reason) include yourself in the area, but not if it’s the middle of it.

However, for homebrew reasons, the character trying to cast Thunderwave has the following limitation to their spellcasting:

[I]f the spell requires a somatic component, it must target you or a point in your space.

Thunderwave, with its components being V S, fits that description, but that results in a rather unclear interaction – since I have to choose a "point in [my] own space" for the spell’s origin, where can the cube be placed?