I am low in all haemoglobin, rbc, pvc, mcv, mch, mchc but a high rdw. my iron is only 1.6 umol/l. is it possible i have thalassemia?

This is serious: If your physician has not already had a serious talk with you about what is probably iron deficiency anemia, get with a physician who's a better communicator. You haven't shared the exact numbers, but the smart money is on iron deficiency, with thal and a few others needing to be ruled out. Even if you have heavy periods / recent pregnancy, you need a competent workup. Demand good care.