I want to get married, but my girlfriend is now panicking...HELP?

My girlfriend and I were going to elope this autumn. Due to certain circumstances within both of our families, that is the only option if we want to have a wedding day to ourselves without drama and heartache. So it was her idea that we get married in secret. At first, I wasn't so sure, but now I am completely on board with this. I want to marry her, and am committed to her. I am certain of what I want. But now she's panicking and feeling unsure, and there's really nothing I can say it seems that calms her down or puts her at peace with our decision (a traditional wedding with family and friends simply is NOT AN OPTION for many reasons, so it's elope or nothing). She says she wants to marry me with all of her heart, but I fear she's going to back out of this. I won't force her into anything, and refuse to beg and grovel for her to marry me (as much as I want this). What can or should I do?