Rosie weighed 2 lbs 6 oz at 6 months and she now weighs 3 lbs 2 oz at over a year old. She definitely filled out as she got older. Her overall size stayed pretty much the same, she's just not as skinny as she was before, which is a great thing! She was so bony and tiny, I hated it!
Luma was like 5 lbs, maybe? And she ended up being like 8 lbs at 2 years old...I dunno, I guess she's a fatty. She is very tall and long, and is built really sturdy. My little porker
but really, I LOVE Luma's size and much prefer it over Rosie's. Luma is just the right size to be used as my personal pillow (against her will) LOL
At 7 weeks, your babies surely have lots more growing to do.