Ferritin reacts to things besides iron, so I would not be alarmed. It's still close enough to normal to not raise concerns. Any infection or inflammation will raise ferritin levels, so they are not a good indication of true iron levels. The iron level should be checked using ferritin, serum iron and total iron binding capacity.
What is most important during thal minor pregnancies is that you take a high dose of folic acid daily, as you are already doing. The best form is l-methylfolate and you should be taking 2-5 mg daily. Natural vitamin E is also recommended to help prevent clotting issues that sometimes occur with thals.