Is it best to feed on both breasts or one at a time?

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When breastfeeding, is it best to offer both breasts or one breast per session?

I know the hindmilk is good for baby and right now I need my baby to gain back the weight she has lost in the first two weeks (she is now 11 days old!!)

I have been just nursing with one breast per session but I have noticed my right boob produces 1 oz when I pump and my left only gets .5 oz!! So I didn’t know if there is something different I should try, or if it is just a preference thing?