Stalls are perfectly normal & are an important part of your weight loss as the others have said. The first one usually begins around week 3but can be before or after this time like yours. They generally last 1-3 weeks & again they can last longer or even only for fewer days. The numbers are based on averages & so just give you an idea what might happen when.
Yes they are frustrating but it’s best to let them ride out. The stall will break when your body is ready to move forward again. Don’t stress it out by making more changes other than those required by your plan so stick to it. Reduce how often you’re on the scales & try taking body measurements. Many notice that while the scale doesn’t move, their clothing fits differently.
Also, if you would like more precise information about portion sizes, macros, etc, ask for them from your dietician. It’s about feeling comfortable & confident about what you’re doing, For example did they say when you should be up to a cup of food? I was told 6 months for a cup but that was what I was told for me.