Hi Indunil and welcome,
First I want to note in response to another post you made, that doctors dismissing those with thal minor and not taking them seriously is the norm almost everywhere. This leaves you with help yourself as the main option and by coming here, you are doing more than you will be doing by talking to doctors about it in the context of thal minor.
I highly recommend that you take some time to go through various threads in the thal minor section and also in the Diet, Nutrition and Supplements board. Your hemoglobin level is lower than most thal minors in general, but typical for thal minors who exhibit more than mild symptoms. There is no quick and easy way to change the way you feel, but making sure your diet is nutritious and taking needed supplements, along with some exercise, can improve your energy level and health in general. Avoid empty calories and try to eat as much fresh fruit and vegetables as possible. These provide vitamins, minerals and antioxidants, and help prevent damage to cells caused by oxidation. This is very important in thalassemia because there is always some level of hemolysis or early destruction of red blood cells, because the irregular, small and misshapen red blood cells are filtered out by the spleen and kidneys, and because not enough beta globin is produced in thal minor, there is a surplus of alpha globin. The unmatched alpha globin chains bind with each other to cause tetramers in the bloodstream. These tetramers also lead to oxidation and their effects need to be countered.
Your approach to supplements should have two purposes besides correcting any deficiencies. Deficiency is most likely to be seen with vitamin D, where 2/3 of people tested are typically found to be deficient. I have dealt with this personally, and found that D deficiency can cause many health issues, including tiredness, lack of energy and depression. Correcting it takes a dose that was formerly thought to be high, but now is routinely taken. I take 5000 IU vitamin D daily, except during sunny summers when I can get good exposure to the sun on a regular basis, so I am taking the supplement about 9 months out of the year. It makes a big difference. Doctors have found that in many patients, 50,000 IU doses at one time are effective in successfully reversing deficiency. Unless you get sufficient, regular sun exposure, it is likely you are deficient. B Complex, vitamin C, vitamin E (natural D-tocopherol, not Dl-tocopherol), magnesium and L-carntine are all important to building red blood cells, extending the lives of these cells and improving the efficiency of the circulatory system and maintaining the health of the blood vessels. Your folic acid dose should be at least 1 mg daily.
This is a learning process for everyone here because there is no guide for dealing with thal minor, so compare your experience to others who have posted here and look for ideas that people present. You have to look for ways to optimize your health, but stay realistic. Don't expect miracles but work on a routine that stays with you and strengthens and protects your body. In the long run you will realize there is a difference.