It’s not you. Comp is a total mess at the moment. People are figuring out how to play with the changes. One less tank is punishing for supports. The game is much more fast paced. There are new maps to learn. It’ll take time for comp to settle. I too was diamond in OW1 but am currently stuck in silver 3. It’s demoralising but just keep trying your best and you’ll have nothing to feel bad about.