You sound very much like a world inside a world person - i.e. in regards to your work at a library and your interests. ENTj doesn't seem likely to me and INTj is of course possible. As is INTp. I think several people write like you, and not just NT types! I couldn't easily type you as an INTj when for example Isha perhaps could decribe herself in similar terms (I don't even know what her self-typing is anymore!). But I suspect you are probably an INTj or an INTp or something like that (because you have poor Si).