Shallow Genital Piercing
Since many genital piercings are self-done by people with very little piercing experience, it is not surprising that they tend to be on the timid side, and find themselves with unacceptably small and/or shallow placements.
Genital piercings probably take more real-world abuse (in a good way for you, but a bad way for the piercing) than any other piercing. In addition, properly done they should bring you pleasure, not problems.
As such, genital piercings should never be done at a gauge smaller than 12ga (many people aren't that happy with their genital piercings until about 8ga). In addition, the placement should be suitably deep so as to allow the piercings to survive the stresses they'll be put under. Finally, abuse of fresh piercings should be kept to a minimum as they will be far more sensitive until they are fully healed.