Thank you for your question. It is challenging to answer this question without photographs or an examination. A possibility is that you may have is a component of a hidden penis (buried penis). This can occur after a circumcision. The issue is not that the penis is physically smaller, but rather it is less visible due to anatomic issues. The anatomic issues can include excessive skin removed with the circumcision resulting in "hiding" of the penis under scrotal skin. Another possibility is that the circumcision resulted in worsening of the hidden penis due to the lack of repair of the congenital (born with the condition) hidden penis at the time of the surgery.
I would recommend evaluation by an experienced male cosmetic genital surgeon. There are several techniques, but the one that I prefer to use is the one that I developed. The results have been presented at national and international meetings for your reference.
Best of luck.
Jeffrey S. Palmer, MD, FACS, FAAP (Cosmetic Urologist -- Cleveland, Ohio)