I don't mind staying mono if that's what he wishes but I need to know should I bring it up again? Will having the open sexual relationship harm my trying to get him to understand what poly means to me, and in general? And will going to poly things help or hurt the situation if I'm just going to get more comfortable with who I am instead of going to find someone else? Really just anything would help.
Do not take on another lover at this point. There is the risk to emotions coming into play.
If you want to be understood, you could communicate MORE with your BF rather than start a new lover thing elsewhere. Could ask him directly something like...
"BF, I am ok being monogamous to you even though I am polyamorous. But to do that, I need to be able to share my inner life with you -- my thoughts, my feelings, poly things I read, want to look at or go visit.
Are you capable of providing me with that kind of emotional intimacy? I don't need another person.
I need YOU, my boyfriend, to understand all of who I am and be willing to share in that. Not just what you find "easiest to take." Do you want to love the authentic full spectrum me or just a limited portion of me?"
Get that sorted out FIRST. And if he cannot provide that, then perhaps best to end it gently and both be free to seek the relationship model that most resonates in the romantic department.
You can still be friends. You don't have to lose each other.