You really do have a great overview of the topic of pentesting and your home network seems to be pretty secure. As far as how secure you want your network to be the sky is the limit. In my opinion there is always a way around all the protections but with your computers being protected against the most common script kiddie attacks I highly doubt anyone would take the time required to further compromise your system (unless your hiding something that someone really wants). As far as whats next I would recommend you jump into a programming language. Any language of your choice of course because everyone has their starting prefference but ruby and python are my recommendations. With this knowledge you can take your pentesting to the next level, and instead of spending time learning more tools, you can spend some time building your own and truly learn whats happening behind the scenes. I too like to learn by research and trial and am currently learning to build pentesting tools using python. Best of luck in your next venture and I can also recommend possibly starting a blog or website where you can post your learnings and ideas, because that can be a great way to get others input and advice on the topics your currently working on.