Every bowler is different when comes to the amount of balls they need in a bag. There are some that feels comfortable having two while others have around ten. It depends on how serious of a bowler you are and if you want to have something that covers every type of lane conditions. One thing you don't what to do is have overlap in your arsenal. It's better to have each ball have their own characteristics and ball motion that's unique and different from one another.
For me, I bowl in two different centers that has totally different lane conditions (expecially when I bowl in tournaments). So one ball will work good at center 1 but I may not get the same reaction at center 2. You say that you're versatile and that's a very good thing. Because being able to change your line or hand position and still put up good scores is always a plus.
