@simrin-- Your infections last months?! Are you sure that they are bacterial and not viral throat infections? Because that doesn't sound normal. I've had bacterial throat infections before and I've always gotten better in a week, at most in a week and a half.
Perhaps you're taking antibiotics too often. Antibiotics actually have a weakening affect on the immune system in the long run. Taking antibiotics at every infection also causes the bacteria to develop resistance to the medication.
I think that's what has happened to you. Next time, try to get through it without antibiotics. Gargle often with salt water, drink hot tea with ginger and cinnamon. Also, I recommend taking fish oil capsules with vitamin E and vitamin C during winter. These strengthen the immune system and also have an anti-inflammatory affect. They will help prevent infections and will speed up recovery.