That sounds like a lot to me, especially since I have known other overweight women who haven't really been encouraged to lose a lot of weight while pregnant.
Overweight women can safely lose weight during pregnancy if their health and nutrition is closely monitored, but how tall are you? That makes a big difference. (I'm about 17-18 weeks and almost 190, but I'm 5'10 and didn't lose baby #1 weight before getting pregnant again).
I would think it would be easier to lose weight earlier on because a woman at a healthy weight is advised that she should gain a few pounds in the first trimester, and then start gaining. Maybe your doctor wanted to set an achievable goal for you early on and once you got it, set a bigger goal.
I would talk to her and let her know that you are overwhelmed. She needs to be careful about setting huge goals because patients could just get discouraged and give up completely. Talk to her about your diet and exercise routine and see if she has any different suggestions to help make you healthier. Honestly, right now, you are probably doing better with diet and exercise than a lot of pregnant women. Maybe you can set different levels of weight loss goals - like the minimum she wants to see, a higher, but achievable one, and then the big it-would-be-awesome-but-I'll-be happy-with-whatever-I-get goal.
To be honest, losing 60 pounds while pregnant sounds kind of crazy to me, but I'm not a doctor. That's about 2-3 pounds a week, which would be hard even if you weren't pregnant. I guess I could understand it at 300-400 pounds or so, but while 220 isn't that great of a weight for most women, it isn't that unusual, either. Just keep up the good work with the diet and exercise and I'm sure you will have a healthy baby.