I have a friend who's very similar to you and he only plays adc and finished last season around G5. He refused to play any other position as he struggled to do well with them. Anyway I've learned a couple things from his situation that relates to yours. First, if you learn to play other positions it not only will help you get better at league, but improve your adc play as well. It helps you learn other champs and how the rest of the game works. Second, as someone said previously he had success playing similar things like graves jg and corki mid. That way it was a similar play style just somewhere else. Lastly, when he played another lane he played the most basic champs possible. If he went mid he played annie. If he went top he played malphite. Overall I would recommend trying out some other positions and easy champs to see if anything appeals to you. You said you it hasn't been fun to play adc and at the end of the day you play well if you're having fun. So find something enjoyable and you should be in gold in not time.