This is outlined in the book "The Rules"
Don't pressure him or even talk about it. I am so turned off when a women starts to question me about engagement/marriage.
Guys are like cats on this, it has to be our idea.
He either loves you and will surprise you when he is ready, or he won't marry you. Either way, you win.
Moving in together before marriage was a mistake. If it is not a huge deal, tell him so, and ask if he would find his own place. You might just be surprised on how quickly a ring shows up. Only do this if this is in your heart, not as a tool to get the ring. You will never feel good about yourself if you "tricked" him into marrying you.
HEY I'M A PILOT
HEY LLOYD, I'm a pilot