I smiled and gave her a nod. I was beginning to like her more, plus I realized we had some things in common. Like our attempts of suicide. The difference was striking, of course. Kate’s problem had been physical, whereas mine had been psychological. Kate had been motivated by an excess of sensations, whereas for me had been a lack of them.
Or should I write instead:
I smiled and gave her a nod. I was beginning to like her more, plus I realized we had some things in common. Like our attempts of suicide. The difference was striking, of course. Whereas Kate’s problem had been physical, mine had been psychological. Whereas Kate had been motivated by an excess of sensations, for me had been a lack of them.
There's something awkward about the wording, but I can't pinpoint what it is.