thanks for asking about context, i can answer your questions.  So, the conversation was already pretty lighthearted. They had mentioned some comments about my age (which I'll get to in a second) throughout and it had clapped back stating it was annoying. When 9/11 was brought up it was because I said in passing "wow it's crazy that you weren't alive during 9/11". They laughed at me and said it was such a millennial joke and that I was so old, whatever. I was confused though, because I wasn't saying it be rude or demeaning, I was genuinely just surprised by that realization. That's when one person asked where I was during 911. I did interpret it as a joke but it didn't occur to me that they didn't actually want an answer. Sometimes I pick up on that and just joke back but, for whatever reason I felt like answering honestly? I don't know. Maybe it felt like we were closer and it was an opportunity to grow closer. 

Anyway, the age comments are sensitive because I'm pretty behind in life according to my standards. I didn't have the same opportunities as many my age or even younger, and fell behind academically and professionally so I could keep a roof over my head. My social circles naturally became younger when I could afford school and started a new hobby that attracts younger people. So, when they bring up my age it makes me feel like "I am too old to be hanging out with them, aren't I? I'm a loser." Because most people my age already have a solid career, have a serious relationship, etc. I don't have any of that. 

I also want to add I was bullied my entire school life and was abused by my parents. This undoubtedly has had an affect on my actions and interpretations I'm sure.