Baby grew only 1cm in 2 weeks

Hi! 2 weeks ago my baby measured 3.5cm and my gyane told me I'm at week 10. Today (exactly 14days later) my baby only measured 4.53cm and gynae told me I'm at week 11+. Feeling really confused and anxious now. 2 weeks ago I was week 10, shouldn't I be week 12 now? If so, is my baby considered slow growth? #1stimemom #advicepls