If you want to visit Balestrand, it will be a bit stressfull, given that your destination is Sauda
Bergen -> Balestrand = 4-5 hours
Balestrand -> Flåm = 2,5-3 hours (not so scenic route, county road 13), 3-3,5 hours (more scenic route, county road 5)
Flåm -> Sauda = 5,5-6 hours (or 4,5 hours if you drive between late june and early september, mountain pass 520 Saudavegen short cut is open)
Sauda is way more south in the country. My tip is to go for a completely different route from Bergen. Going from Bergen to the Sognefjord and Aurland/Flåm, and then return quite a bit. In fact all the way to Voss, and then drive the County Road 13 southwards. This will leave you in the car driving for a total of 12-14 hours, if everything goes smooth. In my opinion, that is a bit much time spent in the car over two-three days, when what you probably really want is to enjoy the scenery.
With only 2-3 days, my recommendation is to ditch the Sognefjord-area, and go for the Hardanger-fjord area instead. It's fantastic, and best of all, it's more on your way to Sauda. A total 6-7 hour drive, that gives you lots of time for stops and enjoy the scenery. A natural place to stay the night(s) are in Norheimsund, or at the fantastic Hotel Ullensvang.