Hi Venkat,
Small changes in hemoglobin are normal. Hb changes with hydration levels and also will test slightly different from lab to lab. It isn't possible at this time to say if some day your Hb may drop. It may drop as you age but it will never drop to levels where you would need transfusion. If it does drop as you age, you might consider some Hb inducing products like wheatgrass tablets. The numbness and tingling is reported by many thal minors and it may be related to not enough oxygen getting to the extremities. Does the numbness lessen with moderate exercise like a brisk walk?
There are many different mutations but not all can be found with electrophoresis. However, if you were a carrier of another mutation you would see some symptoms from the combination. Beta thal and HbE together can cause a transfusion dependent state. HbE should be ruled out in your wife, along with thal carrier state, as it is more prevalent in Indians.
In thalassemia, minor through major, there are varying amounts of defective red blood cells. These are filtered out by the body and one of the results is a buildup of bilirubin. It is possible that this can lead to gallstones. We have had some earlier posts about milk thistle and black onion seeds as herbal remedies for gallbladder and liver ailments. If gallstones become a problem, you might consider a natural remedy before removing the gallbladder. (However, if the situation becomes acute, the gallbladder should be removed). I don't want to scare you, as this is not as likely in minors as majors, but minors should be aware of any potential problems throughout their lives.
HbA2 in intermedias can approach the levels seen in majors...90% or higher. For the sake of reference, an intermedia of your age who does not transfuse would have an Hb no higher than 8.