Prenatal vitamin during pregnancy

Hi ,
My prenatal vitamin contains 28mg iron. I am currently 8 weeks pregnant and worried about the iron content. Last time I checked my hemoglobin was around 11.3.My feritin level was always low(around 18ng/cl) or borderline. But iron level was always good. I result above is more than a year old. I did not get a chance to do a complete blood count lately. My first OB/gyn appointment is 2 weeks later. I will do complete blood test then. I know human body cannot release iron and iron over load can be very harmful. I copied the following from internet
A ferritin test measures the amount of ferritin in your blood. This measure correlates with the total amount of iron stored in your body." If you have a low ferritin count, this indicates iron deficiency-

Read more: http://www.livestrong.com/article/82436-increase-ferritin/#ixzz2Cs7vpafk

I read one of the thal pal post that pregnant women with low feritin should take iron level. I do not understand one thing.  If I take iron supplement is it going to increase feritin  level? Free iron could be toxic to the cell. As I mentioned above I always have good iron level and low feritin level. Now I am worried and confused. How much iron is too much? Any comment s or suggestion will be highly appreciated.
Beta thal carrier.

During pregnancy many women, including those that carry thal minors do need iron during pregnancy. If your ferritin becomes low, iron should be taken during the pregnancy, but only if a ferritin test shows a definite deficiency.  I would suggest you get the ferritin tests so you know what needs to be done.

Okay thanks. I will try to get the blood test soon

The ferritin test alone does not indicate iron deficiency. The source is incorrect. Only by using a full iron panel can deficiency be determined. You said your iron level is always good. If this refers to serum iron, then you should not need supplemental iron. It's best to ask for an iron panel before agreeing to take iron supplements.