Constipated and 18 weeks pregnant

Keryn • Delilah 11/19/18 Juliet 8/13/20 Noah 8/27/21

I have been constipated consistently for over 3 months now. I’ve tried everything and I only go maybe once a week if I have over 7 doses of miralax and milk of magnesium but I’m in excruciating pain when I do go. Is this normal? This is my 4th pregnancy and I’ve never had this issue before but I need some relief more often because I don’t even have the urge to go. Any advice?? 😅