at the outset, the FET Q5 is shown connected wrongly, D&S need to be swapped.
One BS250 cant drive seven segments in case you need to display "8". no current limiter shown either at digit drive or segment drive? perhaps you need a resistor on the drain of each segment drive FET.
Why at all you need the Q5? Can't 2N7000 alone serve? When input is logic 1, it conducts and delivers 13V with a series resistor to the CA pin of the display, instead of Ground. I feel it should be enough. You might need a higher power device for reasons mentioned above.
In general, too costly a design with lots of MosFets.