How to know when or if to switch tank

I haven't been playing overwatch that long but I'm not new to fps games and recently I've decided its time to try comp. I usually play Junker Queen and I've practiced quite a bit with her so I feel as though I don't play her horrendously and I usually don't encounter too many problems, however I find playing her against Zarya (especially), Orisa, Reinhardt and Mei who I know counter her (when the player actually knows how to play them correctly) very difficult which is probably how it should feel but I'm not confident enough to play other tanks but I also don't want to throw. If I'm really struggling with jq I'll switch to Reinhardt, but I know I'm very bad at him so its not really an improvement. So I'm wondering if its worth it to switch or if I should just stick with what I know and if I really should do it. I have been trying to learn other tanks but I don't really like the way their playstyle feels. I would really appreciate any advice given.