in your case, if the her2 is negative, your BC is luminal A. For early stage luminal A type BC, the chemo is optional and the hormone therapy works well. If the her2 is positive, the BC is luminal B.The herceptin is very effective for her2 positive type BC.But the herceptin must to be given after the chemo therapy.So, the missing tumor caused the problem for you and your doctor.I think that the tumor had been removed when they were doing the biopsy. Be thinking positively, nowadays they can do so much for BC, except the triple negative. Do your best, you will tough it out.