Welcome to HCM
We understand your concerns
I went through your details. You don't have to worry much about this issue mainly because penis, cannot decrease in its size, length and girth. There is no physiological or organic possibility of such an eventuality. But, yes. There is a possibility of shrinking of penis because of atmospheric heat, general debility, stress
, physical ailments and hormonal
issues. But these problems can shrink the penis for some days together and when you regain your self, the penis will cone back to its original size. I also would like to point out the shrinkage due to age. when you get older, penis, naturally, will shrink by around some centimeters. That may not be the case now. The vein you see is also normal. The veins on the penis can increase in size due to the same circumstances stated above.
In my opinion, you are just obsessing with this thought because there is no factor as such. You have been given with blessing with such a huge penis size. Therefore, please do not obsess and be worried about possible negatives. Enjoy your sexual life.I suggest you to consult a sexologist
to have more information and clarifications.
If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR. Make sure that you include every minute detail possible.
Hope this answers your query. Further clarifications are welcome.
Good luck. Take care.