Well I’m a few years older than you, but I’d guess I’m fairly “average”
Pairs of knickers - approx 20 (all worn regularly)
Bras - approx 10 (tend to regularly wear about half of them)
Sports bras - 3 (regularly wear all)
Pairs of Leggings - 3x running, 2x regular (regularly wear running leggings, rarely wear regular ones)
Nude tights - probably 1 lurking at the back of the drawer (couldn’t tell you the last time I wore any)
Black opaque tights - 2/3 (Not worn often)
Pairs of pjs - 4 PJ bottoms (that I can think of), and probably around 10/12 tops - none are matching pairs. (The bottoms are only ever worn as loungewear)
Nighties - 0
Vest tops for wearing under stuff - 7/8 (Rotate the same 3/4 - never wear the others)
Slips - 0
Pairs of regular socks - 12/15 (Prob only wear the same 3 as rarely wear regular socks)
Pairs of trainer socks - 4x running, approx 15-20 other (Wear runnings ones regularly, of the others I tend to rotate through the same 8/9 and ignore the rest)
Pairs of thick "slipper" socks - 0