Looking for recommendations on whether i should raise or sell my heifers.

I have a small farm, newish to ranching, and I run less than 10 dexter cows and a bull. All cattle are kept together except for 3 months once calving starts in april. It can get down to -40*C here in jan/feb and only have 1 barn/shelter. I'm worried about keeping the heifers seperate so they aren't bred back to the bull by accident. Would the effort be worth it in the end?

Would i be better off selling any heifers i dont intend breed

-or-

Should i deal with managing them separate and raise them for beef as i would the steers