it has three grooves on each side.
The discription is a little vauge so I'll use a picture
Are the groves along the length of the key, like the one above the letter D here? or are the notches cut into the flat part of the blade? (marked by C here)
Grooves along the key are simply wards designed to control what types of keys can be inserted in a lock. the notches are the heights that manipulate a locks pins.
Assuming there are three notches, and that there's not another that's so high the key just wasn't cut on for that one, then yes, its be safe to think there were only 3 pins
TLDR, What do you mean by 'grooves'?