Slim women lost weight?

I ate quite normally before being pregnant. Breakfast dinner and tea. Loved my desserts. Was still a healthy 58kg. When i went to see the midwife (first appoitment) she was concerned because i was 54kg. And i felt really self conscious, like i was being judged. Seriously woman its like half a stone from my normal weight.. If it were someone slightly heavier than me had lost that, it wouldnt be a problem...