mcgruff

You're fine - keep going. Just take it a little at a time, give the neck time to settle between adjustments, and measure your progress with a feeler guage. When I got my dot the neck was perfectly flat. When I started adjusting the truss rod to add some relief, I seemed to hit a loose spot with very little friction. After a few turns it tightened up again and then the neck started to relax into a forward curve. Here's the frets.com big buzz list.

I'd expect a Gibson 335 to be better - but only marginally better than the best Epiphones with good pickups (OK not allowed to mention that). The amount you have to pay for that last 15% or whatever is enormous though. Epiphone really do make some good guitars which are fantastic value. There can be some issues - poorly cut nuts don't seem to be uncommon for example - but the basic guitar is pretty sound.