Tracey,
I know what you mean. I have a 4 o'clock WI during most of the year and with clothes and the time, I weigh two pounds more than I do at home in the morning. All I can say is to mentally deduct the couple of pounds you are up to find your "real" weight.
Then every week you'll weigh in at the same time and you'll see a reduction of weight as you follow this program. Good luck. I hope you like WW/ (trial and error is one way to go, but I found it was silly to watch what I ate, eat too little, or avoid water on WI days. The best thing for me was to avoid salty foods the day before and just do the regular things on WI. I also wear the same outfit each week when I weigh in so that I don't have clothing as a factor to consider.) Hope this helps.