No need to sweat this. I am not saying ANY handle goes. No, "EscortMurderer" isnt going to cut it. But as you point out, yours is quite benign.
Providers need to know you are not LE and not a nutjob. They can come as close as possible to knowing you are not either by you providing proper refs/verification info. If you have those issues solved, I dont think there is really anyone that will exclude you from seeing them.
To even further your case, you say you dont negotiate. So then, whats the problem? In your case, the girl gets her requested fee and she will see you dont negotiate by your email contact with her.
If she did have doubt by initially seeing your handle, which I doubt, that doubt would be washed away by your ACTIONS, not some handle you chose to hide your real, given name.
Your own limited experience tells you that you are fine with your current handle. As one that negotiates with working girls on an almost weekly basis, I can reassure it will not be an issue. Think about this: girls are checking my refs from girls I have negotiated with. If it was so horrible that I negotiate, they would tip off the the girl I was trying to see. See my point?
If a real negotiator like myself has virtually no problem with seeing the girls he wants, then certainly a guy feigning to be one shouldnt have any problem whatsoever. LOL