I have the same problem, Catrin (shortness). But, even thought the knickers come down to my mid-calf, almost to my ankle, they aren't really "warm." There's no insulation at all. They are just a pair of "long" shorts. I wear them, or knee warmers (which on me are almost leg warmers) when it's between 50 and 65. Below 50, I have tights on. I know, I see some people in the dead of winter, riding with shorts on... not good for the old knees.
When I finally found some knee warmers that fit me, I found I wear them more than the knickers. If the temperature is staying between 50-60 I wear the knickers.