Hello Thanks for your query.You have not mentioned about your marital status.and have doubt in your mind that your penis is shorter when it is in flaccid state.You have mentioned that you get good erection and length of your erect penis is 4 inches in length.
Please note that length of the penis in flaccid state has no significance at all. It is the hardness on erection that is more important in sexual activity and for orgasm of a partner. If you have a problem of premature ejaculation and if you are married or unmarried but want to get indulged in sex with your girl friend then it is advisable to consult Sex Therapist to learn some techniques like stop and start and Squeeze technique.You may take drugs like Phosphodiesterase inhibitors (Sildenafil
) and Dapoxetine
to delay ejaculation You have to consult your family Physician to get prescription of these drugs.