if you are lvl 45 but your exp bar is full does it count as lvl 46 if you didnt go to the level up screen and lvl up yet?

I'm not sure I fully understand. But if you gain a level up, but don't actually level up your character, and keep getting your skills leveled up, they will still keep piling up. So if you finally spend that level up, your "to next level" bar could start out past halfway, or you could have already leveled up again.

No, you still are 45 as long as you don't o through the levelup screen. That means that the enemies will keep at their current level as well, but as lublar said, when you go through levelup screen, your bar will grow automatic, or even give you more than 1 level