She is now wondering if there is any way she could possably walk into the DA's office and have them drop charges.....?
She can try. However the DA does not have to drop the charges because your girlfriend is no longer mad at you. If there are photos of her bruise and scratches, they will most likely not drop the charges against you.
If you actually did strike her, you deserve to be prosecuted and suffer the consequences of your actions.
If you did not and your girlfriend only said you did to get the police to arrest you, then perhaps it is her that needs to be arrested and suffer the consequences of filing a false police report.
Who has trouble keeping their temper, you or her?
Once these fights between boyfriend/girlfriend start, they usually continue. The police do not like being called in to these dysfunctional relationships every other day to play referee and they certainly don't like it when someone calls/uses them when it is convenient, only to decide they don't want to pursue charges when they cool off and are in love again.
Was this the first domestic violence call either of you made to the police?
Does your girlfriend have any prior criminal record?
How about her brother?
Are you back living with your girlfriend?
How is your daughter doing?