Hi Aryaka,
Welcome on the forum,with hb of 12.1 your son can only be thal minor,Thal major kids are usually diagnosed with in first year of their life and they have very low hb,thal intermedia can take long to get diagnosed,but i doubt if any thal intermedia would have hb of 12.1,so he must be a thal minor.
Thal minor is most of the time asymptomatic and people spend their lives with out even discovering that they have it,but it's a good thing that your son is diagnosed because you would be able to give him more nutritious food and avoid iron supplements unless iron studies are done and he is found iron deficient.The most important thing about thal minors is that when they grow up and have a family they should make sure that their partner is thal free,because if both partners are thal minor,there is a 25% chance in every pregnancy that the baby can have thal major.
Is he your first baby? since he has thal minor,you or your hubby must be a thal minor,so i'll advise to go and take a test called hb electrophoresis to determine if you or your hubby or even both of you are thal minors,if you both have thal minor ,you'll have to be careful if you plan for another pregnancy.
Hope this helps.
Zaini.