There's plenty of room inside your walls, and many defense buildings left outside. I'd put them in, keep them protected, this way they'll last longer. Otherwise they'd get blasted away real quick. You can still have the mortars inside the way you want. I don't think your towers are badly placed. You'll start getting attacked by planes in this age, and the way you've positioned them can attack planes from every front.
Anything that is not defensive and not your resource of choice should remain outside so as not to waste defenses. Use those extra buildings around your base walls as padding, to make it harder for your attackers to penetrate. Always check your replays and see how the changes are working.
The 3 layered cake design you're using is usually a good choice, you just have to fix it up a bit to really make the most of it! If you see a friend or foe with a similar base that looks tough, don't hesitate to drive inspiration from it.
Extra tip for anyone who may need it- try not to put many similar defenses too close together, so that it's not that easy for your opponents to deactivate too many defenses at once.
Anyways, feel free to keep us posted on the changes!
