First -
I would remind you that a person cannot sin by accident - sin must be made consciously -
you must know the gravity of the sin and decide - purposely -` to commit it …
Second -
Confession is very good for us ... and even small sins hurt us - so you can go to confession in cases are that are less then mortal

and the more often you go the better off you are … scrupulosity though is not something to strive for …
Third -
do you only have one option - in my location there are evening masses available -
in my own parish now - but also in adjoining parishes -` search out a later opportunity
Last -` do not make this a habit