It's good you feel your hair is thicker. I haven't used Duta, but on Finasteride can also tell my hair is thicker, but the hairline is slower to catchup, specifically the thinner parts, but I do notice growth where it was fairly devoid of hair.
I'll show you what I mean.
View attachment 89706
1. Red triangle, at my worst, there it was basically bald there. What I'm not sure of is if they all shed at the same time due to Telogen effluvium, since it was thin there, but would be real coincidential that it has looked the best since using Finasteride. Now it looks like sparse baby hair. It took about 6 months to look like that, basically less hair in the resting phase.
2. Yellow rectangle is hard to see but has also grown back, albeit the hair is lighter and more sparse.
Can't say the island where the widows peak would be has thickened but I can see shorter thinner hairs, perhaps it's always been there. We'll see if it thickens up, but does not look like it.
Do you have any pictures of your hairline before your hairloss kick in and after and highlight what you're describing? I'm genuinely curious as I think my sister may be thinning on top(middle part on her front hairline).
Specifically this part you mentioned. "the very top of my head with never grows ever"