I don't think it's matters how she's doing it. I'd guess that you're right in guessing that the problem is coming from you
If you were to look at posts similar to this around here, youd find that people gave similar advice. Stop masturbating. Her hands/mouth/feet/elbows/whatever are going to give a much different senstation than your hands would. Most likely a bit more gentle than you are. And you're just used to how you do it.
It's not that this is a problem that you or her have, it's just a little difference between things. So stop masturbating for a few weeks, and you'll get that sensation back
