About baby

Hello everyone!' I'm currently 17 weeks today but when I went to see my midwife she told me I was 16 weeks&1day and also when i went my for my private scan to find out the gender they also said so I now count from there but I also got told she was 5oz at 16weeks&1day an she should of only been 3.5 an babys are only 5oz 17 weeks' could she just be big for her size or could I possibly be further then I think also have a recent picture of my bump X