I gotta say, maybe it's the small pictures, but except for the one when your hair was wet or gelled I could see very very little if any abormal thinning... when dry, it looked thick as a bush. That one cowlick at the crown isn't bad at all imo. I myself am a diffuse thinner...
Now you say we cant see from the pics how thin it really is, you may want to post new pics, a little larger and really try not to conceal it. Can't really give advice until you post newer pics to show your claims because from what is shown I would kill to have your hair...
Also if you have sides, don't increase, see a doctor first. And remember it takes TIME everyone reacts differently. A lot of people see sheds or not increase after a few months and get scared and abandon and their hair is reshocked and loses more hair. Back and forth on finasteride can be a rollercoaster. (I am not on it yet, Just know RL friends and from forums and research. Sort of scared to go on that ride =)
As for shorter/buzz, your hair is pretty short already from the top but cant see it all... but the shorter the hair the thicker it CAN look. It'll 100% look better imo than longer hair which I had and my hair broke more, it was terrible but I was scared to get it cut short (as in a butch cut, 1/4 all the way around). It WILL be harder to break your hairs but you will still lose hairs. AND - it's easier to apply any topical (mino) to scalp. And any sheds won't be as noticeable.
Anyways, post NEW *honest* pics will help more advice! =D Good luck mate!