Don't get me wrong, this is a very common problem for engineers (I'm an engineer and I fall into that trap every now and then). But from the post, what's lacking is actually talking and working head-head with teachers and linguists and people doing language learning research, because, you know... these people have actually spent their whole life trying to teach other people languages. So they might know a thing or two, that an engineer trying to teach himself a language might be missing.