My DS has gone from 9 lbs 6 oz when we left the hospital, to 10 lbs 10 oz at 2 weeks, to 13 lbs 4 oz at 1 month -- and they thought that was fine.
Your LO is healthy and eating well. She is perfect.
I delight in my pudgy babies. I know that means they are healthy and happy and content. DD was always huge (born 10 lbs 9 oz), but once she started walking, all that weight melted off, and she is now actually pretty skinny -- I can see her ribs.