Leveling up in League

Currently, on my account, I have 101 wins and 101 losses. Despite playing 202 normal games, I'm still just barely level 24. I know many other people with a much lower game count that are already level 30. I have also seen in other forums that even without boosts the average normal game count to level 30 is roughly 150-300 games with a W/L ≥ 1. As such, I'm having difficulty understanding why I receive less exp. Does anyone know what the problem could be?