As I understand, he left penning down his philosophical thoughts till a rather late age and wrote the Critique of Pure Reason at a point where he was worried he wouldn’t remember it all and consequently it was done under a lot of haste.

Now I want to really read his writings

Take first Critique, and read it as if a software engineer wrote his ideas now some software might be architected in order order to work as it is working right now: that is the point of Transcendental Argument.