I'm sorry to hear that you are experiencing such a difficult time, but also thank you for getting the courage to post your troubles. I'm going through a similar thing where my anxieties have started to interfere with my daily life, and I've been at a loss to figure out when and why they started to get out of hand. Have you tried to trace back to when your insecurities started to get worse, to see what may have tipped it over?
I'm a fellow newbie with trying to manage anxiety, but I've found reaching out to people is a definitive first step, so kudos for doing so. I know you say there is no one you can talk to, but it does help to have someone you can have a face to face conversation with. Maybe look at the people around you and gauge if there is someone you trust enough to try to open up to. Otherwise even opening the conversation with a GP could help.
And it seems like you're hearing the negative voices in your head, and they are hard to ignore. I've been trying meditation through apps like Headspace - it may not feel like much but if it can calm you even for a little bit it's worth a try. I hope that you continue to find support here in these forums.