I’ve not made it past level 12 or picked a realm to stay on yet and I don’t feel left behind. You put in the time you can and wherever that gets you, there you are. Some players may be ahead of you but I’d wager there are many more people out there that are around your level than there are fully clearing all of the currently available level 60 content.
Stop stressing out about it and play when you can. There’s a good chance the game will still be there for you when you are finally able to reach level 60.