Ready-to-wear sizing is a compromise. A size M is an average of many bodies and an exact match for almost none of them, which is why so much of what people buy needs altering before it is worn.
For occasion pieces we skip that step. After you order, we ask for twelve measurements — bust, underbust, waist, hip, shoulder, arm-hole, sleeve length, sleeve opening, blouse length, skirt length, waist-to-floor and height — and cut from those.
A lehenga takes around three weeks. Bridal takes around twelve, because the zardozi is worked by hand on a frame and cannot be hurried without showing.
This is also why those pieces cannot be returned for change of mind. A garment cut to one person's measurements cannot be sold to anybody else. We would rather say that plainly before you order than explain it afterwards.