Calorie intake and weight goal help!

Over the past year or so I have successfully lost 64 pounds. During the summer I slacked off a bit but didn't gain or lose any and then as the school year restarted I have lost a few more pounds. I have been finding it difficult loosing this last ten/fifteen so I reduced my calorie intake and upped my exercise. I recently went to my doctor because I haven't been getting my period for a few months. They measured me and I was 5 ft 4 1/2 and they weighed me and I was 135 pounds. My overall goal weight since the beginning was to be somewhere in the 120's, about 125 at least but he told me if I go passed 130 that would be unhealthy! I am not overweight right now or unhealthy but I cannot deal with the fact that he is saying these things I know he is a doctor and everything but I have seen people the same height as me go way passed 130. He also said for me to eat at least 1500 calories a day and I am finding that difficult to do as well, but am trying to do it. So what should I do, because staying at 130 my entire life and being "almost there" isn't what I want at all! All advice welcome!