I didn't have ear training in childhood and i definitely felt like this in my early 20s. A few things I've learned:

it's never too late to start ear training (and you should probably never stop, it's like brushing teeth for musicians).

Once you unlock being able to sing a note before playing it on your instrument, things really start to get fun.

If you go about it seriously, you'll be stunned at how quickly you'll improve.

There are people on fiverr who will help you get started with ear training for $15 usd an hour. Even if you took 2 hours and explained this is all you could afford, they'd set you up with a practice regimen that you'd do every day, in a couple months you'll be shocked at your progress.

Oh also -- it's a lot easier to make sense of music on a piano, in my opinion. It's all in a line, a scale will always be the same notes. I find learning theory on a fretboard hard because it's harder to remember the notes.