Hi Alissa!
I feel the same way. I went through a big shed in April & didn't notice the thinning area until a few months later. It's right in the front, 2 inches into the middle part. Anyway, I freaked out. Then I read about women losing their ponytails. I can't tell if there's less hair there than before or not. I asked my mom if she noticed & she said no. (I could tell she wasn't just saying that).
Brushing, shampooing, etc. - all of that makes me nervous. I've heard a million times that losing 100 hairs a day is normal. Before, I never paid much attention to the amount of strands, but now I count them.
What you could do is photograph your head in various places & compare every few months to see if any areas thin out. Or, you could keep written records, but I wouldn't recommend that if it's gonna make you crazy. My hair sheds a lot certain times of the year so my journal will help me know what's normal for me & what's not.
