re:
Well, without being able to talk to you directly in order to really breakdown your lifestyle and family history, I think it is tough to really pinpoint a diagnosis and/or explanation. There are countless examples of men balding or thinning at a young age. Normally you see a clear family history when it's male pattern baldness at an early age but sometimes you do not, especially when the gene for male pattern baldness was passed to the man from the female side of the family.
To me, it appears that you do have some signs of male pattern baldness and generally thin hair. You see thin hair in many men, especially northern Europeans. I would focus your attention on your diet and take a real close look at your family history. Are there other men or women in your family who have naturally thin hair and not necessarily male pattern baldness or female thinning? Is your diet lacking? Are you on any other meds or supplements that could be causing this thinning? Do you have old photos of yourself that can pinpoint when this problem may have begun? There is also the of chance that this is Telogen Effluvium, but Telogen Effluvium tends to be more patchy in nature and not just an overall thinning.
The reality is that your thin hair is either genetics (e.g. you naturally have thin hair or have early signs of male pattern baldness caused by inherited genes) or it has to do with environment/lifestyle (diet, medications, stress etc.). The individual is always their best doctor, so spend some time analyzing your family history and lifestyle. I am sure this will help lead you to a solution.
Again, I do want to make it clear that many men and women have naturally thinning hair and I think your hair looks fine, but you asked for opinions so I gave them. If you want to thicken things up a bit then try to seek out a solution but often times men and women obsess over their appearance and I hope you do not allow this small issue to effect your life.