Yeah go to an endo or good urlogist I would think this problem is either caused by excess estidol, low t, or dht levels
Think about it like this a man in his 80s will not be as large as when he is 18
I am not an expert, but I can suggest several things you may want to talk to your doctor about. 1)Hormone Levels- they may check for free testostorone and total testesterone. They may check for other hormonal imbalances. 2)Depression/Anxiety- this is what created both a decrease in libido in my situation. The SSRI drugs actually helped me reduce some of these symptoms, but I am still not ruling out any hormonal issues. 3)Venous leakage- if you had any major injury or trauma in that region you may try exams to see if any arteries are blocked or impaired in the penis. 4) Medications- you may be on medicine that can be causing these side effects.
These are just suggestions, but questions you may raise with your health care professional.