You're moving in the right direction, and it can take abit of getting used to the rules with the xen. The info leaflet with the xen suggests you should be able to obtain a 5% loss of your total body weight within three months. Looking at your stats, that's still obtainable. If you've been exercising, you may also have gained muscle which will offset any fat loss. Please try not to be too disheartened. You can have a look at what you have been doing, and maybe see if there are some tweaks that you can make for your next month. You can remind the Dr of the 5% in 3 months requirement, and ask for the opportunity to aim for that. A 3lb loss in a month is close to the 1lb a week that is recommended for healthy weightloss.
I hope things work out for you. Your Dr's scales may not tally with your own, you may be surprised when you get weighed by the Dr and have lost more than you think.
Good luck.