Do yourself a favor, get a Sound Pressure Level Meter, they are pretty inexpensive. I got a few at Radio Shack when they were still in business, I imagine Amazon and other outlets might have some for sale.
Set it on "A" weighting and slow response. A weighting approximates the range of frequencies a well functioning hear can hear, and slow response is more averaging as it eliminates short peaks and valleys.
Play music or TV with the meter on and get used to what 85db sounds like both with your aids in and out. Once you can judge that you can better guess whether you are listening too loud with your earbuds.
Of course I'm not a doctor nor am I giving medical advice, so take this as just friendly non-pro advice. It could be wrong.