Hello Mommies-to be...
First of all, I would check with your doctor about the biotin. I am sure it is safe, but I would still check. Before I became PG I had a nice vit regimen going on, but immediately put it aside when I became PG. I will never forget when my friend's daughter was born with a vision problem. According to her doctor, the (whatever name was given for this probelm) happens when woman is in first trimester and it is becuase there is too much (whatever vitamin, herb, whatever...) in her system. That was all I needed to hear. The bottom line is this... Just until you have the baby, maybe you should stick with just prescribed medication.
In regards to the iron pills...
The first three months my hair wasn't doing anything special, but once my doctor put me on iron pills, that is when my hair grew really long and thick. I actually obtained most of my length from my pregnancy. But please, check with your doctor about iron pills also before taking them.
Breastfeeding/shedding... Well, I JUST recently stopped breastfeeding (breastfeed for 16 months). My PG shed began when my son was 6 months. It started gradually and then all of a sudden, I got up and my sides (temple area) were partically bald (no kidding). But now, after using ORS temple balm and vitamin E they are pretty much back in order (wispy hairs).