I'm level 19 right now and just noticed that I'm not gaining Xp for killing anything? Do you think it's a bug?
Can someone let me know if my game is bugged?

Did anyone else get this bug?

Can someone please respond, I'm in chapter 2, whatever save I load, I don't seem to get XP for killing or completing a quest, has anyone come across this bug? Or know a way to fix it?

Do you have the combat log on? It will tell you if you receive experience after killing an enemy. By the time you reach 19, most basic enemies hardly give any experience at all, most of my level ups after chapter 1 were from completing quests.

Only hits are showing up in the combat log and my character screen shows that my number for XP has not changed, even after killing a lot of enemies

Sounds like you glitched bad, which isn't surprising (this game is buggy.) The only thing you can really do is keep loading old saved games until you find one with experience is still being earned and continue from there.

And start doing what I'm doing, hitting quick save every 5 seconds just in case.