I’m not understanding the game anymore. Can anyone help?

Hi everyone. I've been playing Wot for something like 3 or maybe 4 years . Then because of work and other stuff 3 years ago more or less I've just stopped. Now I've started again and the game is simply without any sense. It is not fun because I just don't understand it anymore. If I play my way, I get instantly killed. If I play along with my team mates, they usually rush and get killed instantly. Playing defensive does not earn any exp or hits. Last 3 or 4 hours of gameplay have been like that, no fun, getting killed and losing matches after matches. An example: enemies can spot and hit the shit out of me and I've seen trees fall literally in front of me and taking damage from invisible tanks. I'm missing something? Have old tanks been nerfed? I play mainly with a pershing and a T43 russian because that's were I left. I don't know what to do. I remember having fun with this game, even when losing a match. Thank you for any info. Have patience I'm just a casual gamer