Offer both sides?

My daughter is 12 weeks old (she was born 5 weeks early) and EBF. she takes 5-10 minutes to feed, and I usually only offer one side as I assume she’s done and doesn’t act hungry after. Just wondering if it’s better to offer both sides and whether that will lead to longer stretches of sleep at night or continue one side? She’s gaining a lot of weight and doctors are happy 😊 but she does have some reflux. TIA.