I don't see how the GF's story refutes anything Zimmerman said, with the possible exception of the details of the remarks exchanged (apparently) immediately preceding the fight.
Zimmerman's friend from the neighborhood (Black guy, former CC anchor) is contending Zimmerman followed the dispatcher's advice to stop following TM. The GF's account does not conflict with Z's testimony that TM approached him from behind, spoke to him, then hit him.
In her version, TM spoke first which I think collaborates that to an extent.
Current reports say Z asked for more medical care after being treated by the EMT's but the police decided to him to the station. Understandably so I think. A broken nose or even a gash requiring a few stitches are not something so medically necessary that the investigation into the shooting death shouldn't take priority. Zimmerman went to the hospital the next morning according to reports.
Also, and IDK what current procedure are, but in the past when dealing with a broken nose I was told at the hospital to go home and return the following day when the swelling had subsided. I.e., they wouldn't treat it right away anyhow.
There is no conflicting testimony.
We have only 2 accounts, that of Zimmerman and a witness named 'John', both of whom reported TM on top of Z beating him.
The kid's (Austin IIRC) testimony does not speak to the fight. Depending upon the version, he either saw 1 or 2 people on the ground but mentioned nothing about anyone hitting anyone.
Forensics can be expected to be helpful here. Unless I'm just watching too many CSI-type TV shows it should not be a problem to determine how close, or far away, TM was when shot.
There are published reports that Z's gun had a full magazine when police checked it. According to reports this likely means one of two things: 1. TM was holding the gun when fired so the slide couldn't fully function, or 2. the magazine came loose and couldn't function properly.
If the above report is true and TM was grabbing the gun forensics will be able to confirm it. He'll have GSR from the blowback and likely scratches/cuts to his hand(s).
Fern