Brief Answer:
Normal penis size and shape

Detailed Answer:
Hello and welcome.

I will try my best to answer your questions as well as provide you with some information which should certainly help you better understand all the areas that are unclear to you.

1. The female vagina is sensitive only upto 3 inches, which means penis size of 3-4 inches is more than enough to satisfy a woman. The average erect male penis is 5 inches in size, so I really don't think you need to worry about size sir. You are perfectly normal. There is no guaranteed or documented way to increase penis size sir, and you do not really require it either.
2. Uncontrolled diabetes can result in a reduced libido, which is why it is important to keep your foreplay which will help you get into the mood and also give you a decent erection.
3. Masturbation is a healthy habit, but daily masturbation can result in a reduced libido or a less erect penis when you need to indulge in intercourse with your wife/partner
4. Semen contains mostly of fluid and lubricant, watery semen does not mean your sperm is unhealthy or insufficient. A more concentrated (creamy) ejaculate is seen when a male has not ejaculated for quite sometime and a more dilute one is seen on frequent ejaculation
5. Could you please provide me details of your last sperm count sir? You could attach the test result of your semen analysis or type it out for me, so I could help you with accurate advice
6. There is no way to self-analyse your semen or sperm sir. This can only be done in a laboratory with the help of a high-power microscope. The investigation is called semen analysis.
7. Your penis looks perfectly healthy in its flaccid state

Hope this information helps sir. Do write back to me for any further help.

Take care.

---