Im 22 wwwks 1 day and I'm the same weight as you and my doctor told me not to worry about gaining since I'm bigger and said I should gain the weight in last trimester but not like 60 lbs. I was concerned i wasn't gaining anything and he reassured me everything is still good. He has no concern for my weight since I'm still healthy. Im a little taller than you but both you and baby are healthy and no complications I wouldn't worry too much. That's not right your doctor is threatening you though. He should be more encouraging with his words.