Thank you for your question. There are no medicines to increase penis size. The outer 2 inches of the vagina is most sensitive so as long as your erect penis is 2 inches or longer there will be no problem having intercourse. You may wish to read 'New male sexuality' by Bernie Zilbergeld. This will help you get comfortable with your own sexuality and needs as well as understand better what a woman needs to be satisfied. There are many myths and misconceptions in society which we adopt unknowingly and cause ourselves to feel distressed. This will help you feel more confident about your self and your sexual abilities best wishes