Help!

Morgan
My baby girl is 3 weeks on Thursday. Last week (on Wednesday) she weighed 7lbs 15oz and yesterday at the doctor she weighed 8lbs 10oz. My concern is: she hates using a pacifier, she refuses. I have tried every pacifier out there, from newborn to preemie to nuk and the ones they gave me at the hospital. The doctor told me that the weighted she gained in such a fast time is because she is pretty much using me as a pacifier. I'm assuming the reason why she is awake all the time crying is because she has a constant belly ache from eating all the time. How do I get her to stop nursing so much? I've tried the pacifier and a lot of walking around and nothing seems to be helping. But anytime she is awake she is constantly bobbing and looking for my nipple. I'm a first time mom, so I'm so lost on what to do next. Please help. I'm so scared her belly will explode or something due to her eating so much.