Oh yes, yes, yes - irritatingly, annoyingly, exasperatingly, frustratingly normal!
Prep yourself for stalls regularly on this journey. At 3 weeks. At 3 months.
I lose pretty consistently 100g a day now - 3/4lbs a week. But some days when I think I have eaten perfectly normally I will put on a pound! It goes fast, but water retention, hormones, muscle building all have an impact.
One trick I have learned - often when I am in a stall, is when I will drop a pants size, or a bra size. So make sure you get in the habit of checking that or doing regular same-spot measurements with a tape measure and you will stay smiling!