7 weeks pregnant with anemia

I will be 7 weeks pregnant on Friday and found out a week ago that I am severely anemic, which has developed since becoming pregnant. My ob has me on iron pills twice a day and we will do blood work every few weeks to manage it, but I'm still very worried. This is my second baby and with my first I never had anything like this. My ob said that we may do a blood transfusion near to the end of the pregnancy. Does anyone have any experience with this?