If you can find a decent study guide (online, or, if there's a physical edition, then secondhand copies of it will doubtless cheaply available on Amazon from students who are done with them), then reading that along with the book isn't cheating. Reading notes for something which is fiction and therefore ostensibly 'leisure' reading may seem a bit absurd, but I think it can perhaps be justified. Aside from anything else, it can supply useful context not otherwise easily available to those not living in early twentieth century America and/or part of the high modern literati.

Whether or not you want to invest that kind of effort over and above what you're already doing is your call, though.

It is a hard book. I read it when I was a rather high-minded teenager, surely understanding very little of it, but it's actually a little hard for me to conceive of myself reading something so difficult now.