Well, you should be proud that you did much better than beginners, and you never used browser wallets, nor did you expose your seed on the Internet. The primary vulnerability here is that you stored all of this on a general purpose laptop using Windows and left it connected to the internet with years old files on it. With or without explicit malware, that surface area is large and random. To achieve greater peace of mind, most people ultimately transfer to a dedicated hardware wallet or at least a clean air gapped device to generate seeds. I like your concept of dividing money into two wallets having two arrangements, as this will decrease the risk at a single point. Keep in mind though that simplicity is also security and therefore do not complicate it to such an extent that you cannot pick it up later.