My 15 month old daughter was diagnosed with low iron level. her level was 10.5 in febraury and 3 months later she is at 11. should i be concerned?

Maybe but...: If your daughter eats food with bioavailable iron, then i would not worry a lot. If she does not eat iron fortified cereals, or meats of any kind, then you might have a problem. 5% of all toddler's have "statistical" anemia which is a normal variant. A healthy diet, will keep her with the right amount. If there is a family history of anemia (not just during pregnacy) then discuss with your pcp.