Is weekly weighing of my 7 month old too frequent - some weeks she gains only 50gms and others loses 10 gms.?

She is fed and solids thrice a day. She is small - was 2.2kg when born and is now 5.2kg. Os fine otherwise - catnaps only but that's a whole other issue. Am I weighing her too frequently - what's normal weight gain after 6 months?