I never really got to the bottom of what it is he wanted from me.

Я так толком и не понял... - I really haven't caught properly what he wanted from me.

Я так до конца и не понял... - I really haven't got to the end what he wanted from me.

Я так толком и не понял... - I really didn't catch it properly...

Я так до конца и не понял... - I really didn't get it to the end...

I don't understand what he wanted from me