Definitely take your measurments, it really helps when the scale is pissing you off.

Also, if you aren't in a HUGE rush to lose weight, eat what you've been eating and track it for a week with the My Plan tool they have here.

You're obviously eating maintenance calories right now if you haven't lost anything in three weeks.

You may have gained a LITTLE muscle, but you're surely not displacing fat with muscle at an alarming rate in just three weeks.

Also, when you start lifting, you WILL hold more water because them muscles ain't used to the stress just yet. When they get used to it, you won't retain as much.

Anyway, so try tracking your cals and then chop some off so you know you're in a deficit. You'll definitely see some weightloss then and start to get shredded!

And since you haven't done any exercise/lifting in such a long time, you're going to have the pleasure of some SERIOUS newbie gains in the muscle department even if you ARE in a caloric deficit... which is awesome and very rewarding/inspiring.

Good luck and keep us posted! Start a journal or a gym log here so we can hepp ya out!

Julia