I second trying something from satisfyer. I just bought their curve 2 because it was on sale, and the first level seems very very gentle to me. I turned it up to the max and even though it gave me a great orgasm pretty quickly it'd still say it's more gentle than direct vibrations because the way it works is by air so there's nothing actually touching you, expect that it goes around your clitoris to form the air seal of course.

It might even be worth trying a cheap bullet vibrator or something. Generally, the higher quality, the more vibrations, at least in my experience, so maybe you'll get something with less intensity if you try something cheap? The plusside is that if it doesn't work you won't have wasted a lot of money on it.

For vibrations, if you are using it right on top of her clit try moving it away a little and use it on the area surrounding it instead. I like strong vibrations and anything right on the tip of my clitoris is way too much for me. So right over or under the clit, or to the sides so it's almost lying against the labia instead. All those areas are still sensitive because the clitoris in reality is much bigger than the part we can see.