Try mixing it up for her. After all, nobody likes a tongue lashing!
Make sure you aren't learning all your DATY moves from porn. They show all those rapid clit strokes because it is visually pleasing to the camera, not necessarily because it is pleasing to the woman.
In reality, ladies feel free to weigh in here, but really good pussy eating would make for boring camera views because you gently suck most of the vulva into your mouth and internally suck, swirl, and flick everything in your very wet mouth. All you would see is the back of the guy's head plastered into her lap. That won't sell much porn.
Obviously, all women are different and need different touches and maneuvers, but I am pretty sure none of them like your tongue bashing them like you are whitewashing a picket fence.
The lady the OP mentions might have a condition (or--gulp--may have seen too many guys before him), but it might have also been her way to politely nudge him to try something else because whatever the guy was doing may not have been quite working?
Remember this is all fantasy, and their job is to make us feel like a God BCD. If you really want honest feedback, you should probably give the lady permission to do that and assure her that it is a service you are requesting as part of the session. That is the easiest way to pick up pointers, if you are a gent that genuinely cares if his DATY is effective.