Weaning off breastmilk

Di

Has anybody started to wean off breastmilk yet? I start work again in about 6 weeks and work 12 hrs at a time with an inability to regularly pump. So.... my breastfeeding journey has to end. My LO takes bottles and I have lots of stash. I was planning on breast in am and before bed for a while and bottles only in day. I guess what I am most worried about is how to slowly decrease pumping frequency to prevent mastitis. Anybody have any experience with how to do this?