sexual satisfactions is largely depend on mental preparation and your interaction with your partner.
Size of the penis is not relevant to the sexual satisfaction. About answering your question phimosis
dose not effect the penis length but as some time it can cause pain cause and even swelling in the penis if the tight foreskin move and stuck in the penis.it called para-phimosis.
As your partner doesn't found an issue about that you also try forget about this and try to enjoy the life . Talk with your partner if he also want to get rid of it there is small surgery where it remove the tight foreskin.
Wish you healthy and happy life for both of you