Instead of finding out how many exp points are gained, look for how much of a percentage you gain.
Like OldBlueDragon said, mouse-over the exp bar before and after a fight to see how much you are getting.
If you are getting 2-5% per kill, stay there and keep fighting!
If you are getting 1% per kill, it could be better, but it's steady progress.
If you are getting barely a movement on the blue bar, time to look for better and tougher mobs.