Can somebody please help me. Tell me what I'm doing wrong idc I don't want to quit this game

I got to gold in april. Was even in gold IV for a while 1 win from gold 3 and I have no idea what happened but I lost a good few games and my mmr hit the tank. I just can't seem to win. I play normals with my brother and the entire game is plats and diamond. The response level is so different I can't even adjust to the silver response level (I'm usually the only Gold in my game maybe one other and rest silver). What am I doing wrong? I main support and top, I probably just need to grow up and play adc again, I haven't touched adc since the start of the season. I can't carry games as riven anymore probably because of the meta I really don't know. any advice would help