Can you tell if you are in tune with something you are playing along with?
No shame in using tab rather than working out by ear, but play along to songs and try and focus on making your playing and the original 'merge together'. This is easier with stuff with clear, undistorted basslines and simple melodies e.g. country,. rock'n'roll, blues.
Try playing simple, riffs.
Play one riff over and again, and then stop and try and 'play' it in your head.
Then try and play along to the sound in your head.
I learned what major and minor triads sound like that way, by treating them as three-note riffs, and when it clicked it was liberating.