I had diffuse hair loss all over my scalp at 30. My hairline was OK. My thinning was noticeable when separating my hair. But, when I combed it right, it was not very noticeable. I thought I would be completely bald and was worried. However, this year I turned 60 and have about as much hair now as I had at 30, and it looks pretty good. So, the point is that thinning does not mean balding. Some men thin out like a woman, and it just stops thinning. Instead of having their lifetime hairs in the back, they have them all over the scalp.
You’re right, but what you’re describing is seen in a minority of men. Some people have low hair density hair with a fine character, and this combination is particularly bad for a see-through appearance. Could this be you?
If we measure the bulk of your hair on top and compare it to the bulk of your hair on the back of your head, we can determine if your overall thinning was something that was always present versus a variant of the balding process, much like the presentation in women.