Occiput miniaturization?!

[mimosa]

I'm 24, and I think I have been losing hair for at least 6 years.

It seems as if I have AGA, as my hair is very thin on top and I have a sort of diffuse bald spot at my vertex. However, my entire scalp is thin, and wherever I part my hair, the part is wide.

I have noticed "miniaturized" hairs coming off the top. I know DHT can affect these follicles. However, I've noticed that some miniaturized hairs also fall off my occipital area! These hairs are less than an inch long, very fine, and almost invisible because of very little pigmentation. Some are a couple inches long, but also very fine and unpigmented. They all have smaller bulbs than thicker hairs.

The diameter of my shafts vary throughout my head. I have both thick and very fine hairs all over my scalp, not just on the top. Some of the extremely fine strands manage to grow quite long, though. Is it normal to have shafts of varying diameters naturally, or is it always indicative of DHT attacking the follicles?

I don't have PCOS or any other symptoms of hyperandrogenism. I fear I may be hypothyroid because of other symptoms like no sex drive, extremely dry skin, mild depression and lethargy (I actually noticed these symptoms before my hair loss). Last time my TSH was normal, 4.2 (ref. range 0.5 - 5.0).

I've always had thin, fine hair. I think my hair passes as normal because people never make comments, or if I mention it, they say it's not so noticeable. Some even compliment my hair! But my part is a little wide and the thinning is somewhat apparent around the vertex, especially under harsh lights/camera flashes.

Some pictures: http://imgur.com/a/zzNjY#0