Congrats sa second baby, mama! Honestly, at 1 year and 8 months, you can start mixing, give breast para sa comfort niya, pero introduce the bottle more often so he gets used to it, kasi pag pregnant ka na talaga, it's harder on your body din. A few of us tried doing morning and night breastfeeding lang, then bottle for lunch and afternoon, and our babies adjusted within a couple of weeks, key lang is consistency at patience kasi some toddlers will reject it at first pero they come around. Make sure your partner or yaya feeds him from the bottle para hindi sya lagi umaasa sa'yo, and wag mo syang i-pressure, let it be natural lang. You're doing great managing two pregnancies overlapping like this, kaya mo yan!