Items are located in the “bra” section, as a work around for my other mod (featuring breastless corsets) the item slot used is ear rings. To remove the nipple piercings, you must navigate and remove ear rings. It might be a slight pain, but this method allows nipple rings and a top piece at the same time.
Most people find clit piercings to be very sexy also its great stimulant for your sims. You can access clitoris piercing at the Accessories section. No expansions are needed.