Based on what I have calculated, tomorrow is the start of the 6th week. I have it checked on the 12th, it was in my mid-5th week.
I am very worried right now as besides the 水(long), there is another thing which also looks like a 水(long) or a bunch of grapes. Both doctors said they didn't know what it is. I have to have a re-check later. A doctor said it could be a 葡萄胎, although the possibilitiy is quite low.
I feel nothing special but a little bit tired. I get hungry frequently.
You may not need to wait for 3 weeks. 2 weeks would be enough to see a big development.