I think that without more information you should trust what your surgeon is telling you. I assume your hematoma was drained surgically, not wrapped with an ace bandage or surgical bra. I assume that until you developed your hematoma your early result looked relatively symmetrical. I also assume that if your breasts didn't match exactly before surgery, different size implants improved on your symmetry, and that exact symmetry was NOT achieved nor was that a reasonable expectation. I assume that your left breast does not have a hematoma of its own, because if it does and was not drained as your right one was, that could account for some of your present discrepancy. As you can see, there are more questions than answers without the benefit of more information or a physical examination. Your surgeon has this advantage, as well as knowing exactly what went on in the operating room at surgery (both times).
So for now, you should be patient, and follow your surgeon's advice. Best wishes!