If you want to do more than "just calculate" (as either Feynman or N David Mermin once might have said searching for the origin of the famous quote ) one of the best ways to flesh out your insight into quantum physics, IMO, is the recent, short and very readable "Beyond Weird - Why everything you thought you knew about quantum physics is different" by Philip Ball (an editor of the journal Nature). Even some profs of theoretical physics have acknowledged that it was the book they wished they themselves had written.
He gets to grips with the niggling questions that always arise as you start working through the subject and I've found him particularly good on decoherence and the measurement problem.
He's clearly thought deeply about the subject over a long time and his editorial experience gives him the edge in explaining difficulties that mere calculators gloss over without a second thought.
I think it's a great adjunct to any introductory course in QM and should be on reading lists.
It's available on Kindle (cheaper in the US than the UK right now 01/01/19) https://www.amazon.com/Philip-Ball/e/B001H6P9SO/ref=sr_tc_2_0?qid=1546371784&sr=1-2-ent