I think you are rocking this!!!
I'm going to assume that your technique for sawing is perfect. 😀 But saw's are always rough. So, saw further inside your line - maybe 1mm. Then use the chisel for finishing the cut.
I'm still amazed you got it that good on the first round. Treat that as a success!!
You should have seen me, I tried everything in my power and kept changing between chisel, saw, knife and box cutter to try and get even lines 😂
I've been there. I feel your pain/sorrow/frustration.
Soon enough, you'll be making some of these.