I can

Like the title says, I cant seem to keep a conversation going. I have started to notice this since I was around 8th grade. Ive had the same friends since 8th grade, and i think this is largely due to the issue that i have. Whenever a social situation presents itself, such as when a classmate wants to talk and starts the conversation with Hey, how are you doing? I always find myself saying the same thing over and over again (Im fine, how are you?) and then their response is the last of the conversation because I end up feeling anxious or flustered. I dont know how or why I started being like this and I dont know whether its actually anxiety, depression, or something else because Ive never actually been brave enough to talk about it with my doctor in fear of being told that its just me sabotaging myself or something like that. I think that thoughts largely due to the fact that my mom (someone I entrust with all my struggles) has told me this whenever I try to share some issues I may be having with my mental health. I have resorted to keeping all my mental health issues to myself and isolating myself from the outside world (including my close friends) which I find is quite comforting. I dont know whats wrong with me, but this community seemed like it suited my worries the best. I hope I get some responses.