Hi,
Your doctor is correct. The severity of sickle cell beta thal is dependent on the mutation of the beta thal gene. Beta zero will produce symptoms just like sickle cell disease, while beta plus and sickle cell will present as a milder condition. I will say that the only way you can know is to get tested yourself and find out what type of beta mutation you have. An amnio, of course will tell you what the baby is and you would also know from that, but if it is 100% to keep the pregnancy, there isn't much point in an amnio. It won't make any difference. You would just know sooner. Many people of Asian descent are not beta zero carriers, so I wouldn't assume anything based on your heritage. If the child does carry both genes, it may be dependent on transfusions. Treatment for sickle cell beta thal is much the same as for sickle cell disease.
There is a drug called hydroxyurea which is used to help raise the hemoglobin level in sickle cell patients. There is a new drug in trials that offers much more hope in raising the Hb to a manageable level. Trials have been very encouraging, so this should be added to the list of treatments that will be available in the coming years. If your child does carry both genes, you can expect treatment to improve greatly in the next decade.