Something else to consider is if you are Last Hitting.
When people start in LoL, they assume it's just one big PvP game, but it's rather deeper than that. If you just run after enemies rather than staying and farming while making sure to get last hits, you just end up stagnating while the enemies get stronger. Unless you get the kills and farm that way, but here's an exert from Gentleman Gustaf's "Gaming like a Gentleman: Laning"...
Why else are lanes important? Minions (and their precious gold and experience) march straight down the lanes, like sheep to the slaughter. Let’s think of it this way. You’re stranded in the jungle, starving and nearly out of food. You come across a small clearing. On one end of the clearing is a bush of berries, and for good measure, freshly cooked bacon. On the other end is a lion. Which one are you going to have for dinner? Well the minions are like berries (and bacon). They’re just there to be eaten. Champions are like lions. They may give you more, but they also might bite your leg off, and you like your leg.