You should not feel embarrassed just because of your penis size if you are sexually fit and active. Small penis is also functionally active and is able to have kids successfully. Hormonal deficiency, chronic weakness or over masturbation etc can be the cause of small size.
Size of penis is not a problem for couples. It is the personal understanding and needs between them which forces people to think about bigger penis and more pleasure.
Sexual satisfaction is not only dependent on the size of penis but it is more on personal understanding and emotions.
Sexual satisfaction is the height of love and emotions and it cannot be measured by penis size only as a factor.