My cans only have two sardines in them too. They are about the length of the tin, and about 1 inch across. Would it help if I weighed them? 
That is what mine were like. I assumed they weighed 125g as that is what it said on the tin!
Annette the srdine-bore here.......
my cans say 120g one side, then 84g drained weight on the other. So maybe 3 sardines then?

??
I know it seems like I'm fussing. But as a pretty much overweight lady I have always been pleased that our dog, at least, tends to be lean rather than fat and I don't want to turn him into an un-fit fatty now. On the other hand, he tolerates hunger very badly. Since we changed to three chicken wings for dinner he has been better, but I am giving
about 190g food per meal, roughly 170g meat and 20g veg. He is thrilled with those amounts, but it's too early to tell whether it is putting too much weight on him.
He's 13kg now, but being 1/4 working type he is much longer than the average show type cocker, and is very lean. You can't see his ribs, but you can see defined muscle groups in his legs.