Erm... you using Lubitel 166+ with the 35mm "kit" I suppose??
Though I don't have a Lubitel 166+ but if I am not mistaken, the "frame" is bigger than the standard 35mm format of 24X36.
The Lubitel 166+ should be ... 58X33 ?
So, it's wider (includes sprockets) and taller? which means less shots per roll?? Cos the exp on the film rolls are counted by the 24X36 I think...