I think it's normal you seem to have fine hair but a good amount of it. Like other have said your probably just maturing. Just keep an eye on it, no need to do anything now
Yes it’s normal and no you didn’t lose hair.
Yes you have perfect hair and no you don’t have to double check.
All is well.
I took a close look and to me you just have wonderful hair
Best thing is you know your hair better than anyone, if you feel something is up it probably is. Go get checked out and don't take random people's word, they don't know your hair like you do. They only see you hair now and it's better than theirs so they say no problems, but doesn't mean it could be going downhill.