OP: You're joking, right? How is that cheating in any way?
I don't understand this 'ear vs. chart' or "feel vs. theory' thing. It's like suggesting an actor could only properly learn Shakespeare by watching the play over and over. No scripts allowed!
Its a big difference. Depending on whether you're trying to learn to read charts or trying to learn to play by ear.
Some can do one, some can do the other. You'll never get good at one practicing the other.
To the OP. Define learning to play by ear.
Are you listening to the song without a bass in hand, trying to figure out the song? Or playing along with the song to learn it?
I tend to listen first, try to figure it out by ear. Then grab the bass later to verify, or to figure out something I couldn't figure out by ear. Really, playing along should be enough to verify it is what you thought it was.
Charts are iffy, no guarantee they're correct depending on where you get them. Lots of sheet music has simplified or smply wrong changes. Fine to use them to help when you get stuck, but make sure they're right. Your ear should be the final judge.
Keep at it, but if you're sure you're stuck, no problem checking a chart for help. Trying to figure it out for a while should help get that pattern embedded in your mind, and you will stand a good chance of remembering it, and the solution next time. So don't cave in too early, its good to struggle a bit. Just don't stay stuck for weeks. The more you do it, the less you'll get stuck.
Helps me to just assume every song is in C while learning the changes strictly by listening (or pick any key you like). Or think in terms of I V VI IV, etc. That lets you learn the structure and recognize similar patterns in other songs. Its not as apparent if you think C F G in C and A D E in A that they are the same progression, just in another key. Much easier learning to recognize the changes and intervals by ear like that. Then take advantage of the bass being transposition friendly and you can play those in any key.
Randy