I suspect there are many many reasons that people are sexually responsive to different degrees. The cliche that has a fair amount of truth is that the brain is the largest sex organ. (Possibly not true with some members here-inversely proportionate?). But we know that during development testosterone effects brain development and clitoral size. The question isn't anecdotally is your clitoris small and can you orgasm. The question might be tested as how many women achieve orgasms easily through vaginal intercourse if there clits are wider than 5 mm and use women with clitoral width of 2 mm or less as the control group. As a man that has had the same experience with my ex(very small-difficult to achieve) and current wife (about 1cm wide-achieves easily with indirect stimulation) and an active and observant swinging lifestyle. Most clits I see (I'm also a gyn) are less than 5 mm.