Herbal supplements are not my expertise, but, through experience, I have found a few that have helped me during pregnancy. Maybe you could benefit from my experience.
Yellow Dock: I was anemic during my first pregnancy. You need more iron when your pregnant so anemia is common. When I was in my third trimester, my OB put me on an iron pill. Iron pills aren't great on your digestive system, and I hated taking them. When I became pregnant with Julian, my pastor, Clara, suggested I take Yellow Dock to help with my iron absorption. My midwife approved and encouraged me to eat lots of high iron food like spinach. Between the herb and topping baked potatoes and pizza with spinach, I never became anemic. Yellow dock promotes regularity, as well, and does wonders for you hair and nails. What a difference from those horrible iron pills!
Evening of Primrose: I've been overdue with three babies. With each one, I'm doing everything I know to get labor going. With Schroeder, my midwife suggested I use Evening of Primrose orally and internally to help ripen my cervix. I only took them after 39 weeks. One never knows whether you would have gone into labor anyway, but lets just say, Schroeder was born after a very short hour long labor! I'm confident this stuff did something.
Of course, talk to your doctor before taking these herbs. Keep in mind, though, that many doctors are not well versed in this kind of information so you may want to locate a doula or midwife who rely on herbs more regularly.
I would love to hear any of your herbal remedies!