Struggling with Depression and Overthinking

Hi, I’m new on here now. I know a lot of people have depression and it comes in many different ways but does anybody else have I don’t know a pacific name to call it but you overthink so much you end up having a argument with your own brain my brain don’t switch off I automatically think the worst of things I automatically think negative. I don’t want to think negative it just happens and I don’t mean to sound rude, but I really hate it when people say it to. Someone like myself is depressed. Oh come on let’s think positive you need to stop overthinking, if I could do that, I would put it in a bottle and sell it over this Christmas period was the first time I spend it alone and I was ill as well. I have never felt so low in such a long time and I get frustrated with myself, so don’t know why I’m feeling so low, and then my brain just starts having a dig all the things that happened to me in my life so please if anyone feels like depressed talk out on here to help to help each other. I just want the conversations in my head to stop. I’ve been waiting for counselling for two years I’m on sertraline I stopped it for a couple of weeks cause I had that chest infection and SARS thing is going round. Sorry people