If she's been hanging around her hotspot then she's been nicely warmed upWhen my bp has been curled up in his warm hide he feels warm, if he's been in his cool hide he feels cooler.
As for your hot spot reading 86, for clarification is that the surface temp under the paper towels inside the tub it's reading? If so and that's the hottest surface that your bp can touch you may wanna crank up your heat pad temp up until the hot spot reads closer to 89 or 90 (just not over 92). For example I have my UTH set to 94 for my pvc enclosure and I get a nice 89-90 hotspot.
Also how flush is your heat pad against the bottom of the tub? I find that sometimes the thermostat probe will cause a 'arch' or 'bubble' and not have some parts of the heatpad rest flat against the tub and that will sometimes not make things heat up as effectively.