Don't do it.
At least not right now. Not knowing the circumstances of your "break", I can't comment as to the actual effect a proposal would have at this point, but a "break" is almost NEVER the guy's idea so I'll let probability be my guide. You've been together for 2.5 years with this girl and the "break" was likely predicated by something she can't get or get past, as your "kick in the butt" comment implied. That's not a good sign of a successful marriage, regardless of how often you two may have spoken about marriage. There are no "breaks" in marriage.
And frankly, 2.5 years ain't a whole lot of time for two potential life partners to get to know each other. My own brother and his GF of three years took a "break" when he was in college and after the "back-together", they took another 2 years to figure out that they weren't ever going to be apart. The message here is "Don't jump the gun". If she's into you for all time, she'll be into you whether or not you're married to her. That doesn't mean she'll wait forever for a proposal, but if she won't wait at all then that's more about the wedding than it is the relationship and that's simply a doomsday clock a' ticking.
Two people should end up in wedlock only because that's the obvious next step and it needs to be obvious to both parties. SunDeck's response was very telling in that both he and his wife obviously felt already "married", so it was obvious that they should get married. It doesn't appear to be quite so obvious for you two right now and it also appears, via "break", that you guys have some things to work through before "obvious" happens. So take the time to work through them before potentially setting yourself up for disaster down the road.