You had four posts that were duplicates (in two pairs) where you were promoting your library. In two of them you didn't disclose your affiliation as per the FAQ.
In addition to not disclosing your affiliation, you shouldn't just copy/paste links to your library on any post where it seems relevant. If those posts are duplicates they should be closed as such. If they're not, you should take the time to explain how your library solves the specific problem stated in each individual question.
Finally, concerning this:
Isn't this part of SO's mantra: if you can't find a good solution, make your own and report back to the community?
In all of the cases where you posted a link to your library, there were existing answers that had been there for months. This isn't a case of "can't find a good solution." It seems rather like you just wanted to promote your library. (Which is fine, but stay within the guidelines outlined in the FAQ.)