You’ve excluded White-legged Damselfly (Platycnemis pennipes). Now another species can be selected or excluded based on a handy gender-neutral feature: an S8 tail light.
Is there a tail light on the dorsal side of S8 only or not? If the dorsal side of the abdomen is black throughout except for S8 only, then you have a Blue-tailed damselfly (Ischnura elegans).
[Note that in some of the female colour forms of Ischnura elegans the tail light is brown, sometimes quite dark brown, rather than blue but it’s still not the black of all the other segments.]
Blue-tailed Damselfly: tail light on S8 ONLY
NO tail light restricted to S8