Finding sexual satisfaction is an intimate art between you and your partner. Perhaps a longer penis will be able to stimulate more areas of the vagina, and maybe not. The point is one needs to be in-tune with their body and be able to communicate that to their partner. There’s no rocket science here but a classic case of trial-and-error, and opening yourself to new experiences.
Journal Source: Costa RM, Miller GF, and Brody B. Women who prefer longer penises are more likely to have vaginal orgasms (but not clitoral orgasms): Implications for an evolutionary theory of vaginal orgasm. J Sex Med 24 SEP 2012