Looks like you need to learn to farm much more efficiently. 225 in half an hour isn't horrible by any means, but it's also not great. If you can, aim for 80-100 per 10 minutes. You won't achieve it every game, but set it as a goal for yourself to work toward.
Kills aren't everything. All that matters in the end is whose nexus blows up. Work on ending the game more quickly if you can; stats like yours usually indicate that you're playing solo for most of the game, rather than coordinating with your team to get objectives. Learning strategy and cooperation is the next step to improving once you have the mechanics down.