I would recommend that you be careful with any answer that you get from another patient because there are so many variables involved into seeing the difference between shapes, projections and sizes based on your starting point and amount of overlying breast tissue. Each patient has their very unique response to implants and cannot be compared from patient to patient. I would seek counsel from your plastic surgeon about their experience with your starting point. Good luck.
I am sure that you will be able to find patients who have undergone revisionary surgery and increased their implant size by 150 cc and were pleased with the outcome. However, the exact same operation will not necessarily achieve the outcome that you are looking for. In other words, their experience may not be relevant to your situation. My best suggestion: communicate your goals carefully with your plastic surgeon. In my practice, this is best done using goal photographs. He/she will be in the best position to advise you about the pros/cons associated with revisionary breast surgery and exactly what procedure and/or size/profile of breast implant would be necessary to achieve your goals. Best wishes.