Puppet, I'm linking to your breakup thread because this really needs the context of your breakup http://www.loveforum.net/threads/83204-Is-there-anyway-to-get-her-back?highlight=
She's delusional if she thinks you can just waltz back in with her as if nothing went wrong. Frankly, taking your time and watching carefully is eminently sensible.
I'd be very wary of taking back someone who thinks that they can toss me out like yesterday's garbage and then have me back without me being wary. Her actions tell me that she's got some huge sense of entitlement happening. Not to mention that she seems to have no concept of how she hurt you. She's acting like a spoiled brat.
On top of all this, it seems like she's still rushing to have marriage and the whole thing. I strongly suspect she's more in love with the idea of marriage than of the idea of being with you. You're only 23 - please listen to your gut feeling.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.