Please recommend a prenatal with no iron

I get extremely constipated and I realized my last pregnancy I was taking a prenatal with iron and would go 3 weeks without pooping ...sorry for tmi lol. But anyways this pregnancy I have a 1 year old imstill breastfeeding and I started the same prenatals and it even constipated her. So now I’m trying to find a good prenatal without iron. I just took my last gummy naturemade prenatal without iron in it so maybe I will just get that one again maybe it was spring valley actually not nature made ..🤔

Also- I was taking miralax everyday trying to not be consripated and that’s the only thing the dr said was safe. And it didn’t work. I actually went 3 whole weeks without going and had to give birth that constipated