So I have epilepsy and take 1200mg per day when not pregnant and 1500mg while pregnant, I usually…

So I have epilepsy and take 1200mg per day when not pregnant and 1500mg while pregnant, I usually take them all at one time before bed so im not extremely tired during the day. I'm going to breastfeed during the day and then feed pumped bottles at night since that's when my levels are the highest(btw I got the okay from several doctors to breastfeed on it).. So I'll pump in between feedings during the day for the night. My question is how long can breast milk be refrigerated for? And can you use bottle warmers on breast milk bottles?