Hey Dimitri, Ok so I wouldn’t say that your current technique sounds incomplete without the hip rotation but it may help you in certain situations or certain types of shots. I personally don’t really think about hip rotation on every shot at all, but if I have more time for example when playing against a push on an open up shot, then I will try to add the hip rotation to generate more spin and power. It definitely does feel a bit strange when you first start thinking about using your his more and just take some time to get used to this feeling I found.
I think if you are in an open topspin fast rally then the hip rotation becomes much less of a factor as your time is limited but when you have a slow block or a push coming at you this is when I would suggest trying to focus on the hip rotation, and it can be quite a small amount in the beginning as well nothing to major. This way I think you’ll be able to gradually add it when you need and have time but also not worry about completely changing your whole backhand. I hope that makes sense and any questions just let me know.
Cheers, Tom