It only went to one sorority, so I'd stop stressing about it, especially if it was someone you know well and she gave you a nice rec. Just get a good head shot for the rest of the groups and go from there. If this is a
SWYAPNR, you need to get going on the rest of them for all the sororities at your school ASAP.
People more schooled in recs than me: Would it help for her to have the writer of the aforementioned rec send in an updated photo, or will that just point up the prom photo even more?