milk of magnesium?

i took 30mL at midnight last night and i woke up around 3:30am and still didn’t need to use the bathroom so i took another 15mL. it’s about 7:30am now and i still haven’t passed a bowel (it’s been about a week since i last passed a BM).

how long does it take to kick in for extreme constipation? how much water do i need to drink with it for it to work? should i take more? i’m 23 weeks pregnant and don’t want to overdo it.

i have already tried the natural route.