robin--I would get a CBC to see what my Hgb level really runs. I'm not sure that the tests they do at the blood banks are real accurate. If my Hgb was an 11-12 I would not be giving donations. Looks like you run a borderline Hgb, 12 is anemic. Optimal Hgb for a female is 14, normal range is 12-16 and you are on the low end of normal if I'm understanding your post correctly. You should listen to your body because it is telling you something. That is how I feel after having a period, not a good sign. Sounds like it's too much loss for you. Doctors are not too concerned because it doesn't effect them, sorry but true. I complained 2 years ago and didn't get any help other than BCP's offered that I refused to take. Now I'm ill thanks to that doctor not treating me.
I would try once a year donations if necessary and keep regular CBC's to make sure you are not becoming anemic. I would ask for a Ferritin test also to be sure that your stores are not being lowered by this donation process or anything else.
If you are still having periods you need to be extra careful if they become heavy, they don't even have to be heavy to make you anemic.
I can't say about anemia as a child because that is usually due to diet and growth spurts. May or may not be related to this. You are smart to be concerned. FLFLOWERGIRL