I'm super late to the party and I hope everything is going well on your side.
I'm not a parent, but I find the info at PCRM generally helpful and mostly fact based.
They also have a little section about plant based diets and pregnancy: https://www.pcrm.org/good-nutrition/plant-based-diets/pregnancy
All the best!
Just as a sort of PSA: You will get no omega acids from WHOLE flax seeds. You need to ground them up first! This should be done shortly before consuming as the ALA in the seeds tends to oxidize when exposed to air.