I run into the same challenge when I buy pants; my waist is at the end of one size range and the beginning of the other.
What I found made the difference was not the waist, but the inseam size (measure from your crotch to ankle). Sometimes the smaller waist size didn't have enough inseam length for my legs making them both a bit short and tighter around the butt and crotch.
Check the inseam size against your own; as Najohn said, the small waist with a longer leg (inseam) may be what you want.
The Tier One Tactical Operator
Tippmann Arms M4A1
KWA USP .45, KJW P226, KJW hi-cappa