the base you have right now is a square base , if they make a hole in your walls and they put like 100 barbarians , they can destory everything , i will suggest you to go to youtube and putting thropy or farming base for town hall 5 , it will show you allot of better bases , and you can use one .
At this point in the game you shouldn't be focusing on winning defenses. Forget all about whether you win on defense or not. What you need to do is farm and build up your defenses so that they are strong enough to defend against tough attackers.
You need to understand some basic base building concepts.
1) Don't stuff everything in one set of walls. Compartmentalize in smaller sections. 3x3, 6x6.
2) Don't put your splash damage right on the edge for a few barbarians and archers to take out right away. Centralize it, and protect it with walls/structures.
You're TH4, you're going to lose defenses regardless, but you can build a much better base and have more people Next you and look for a weaker defense to attack. I guarantee you, anyone that comes across your base will attack it 100% of the time if it has resources. With a better base design, people may still pass.