Juliet, welcome! MOST of us are coming down off the Christmas/holiday carbfest right now, so you're not alone! It took me several days after getting back OP (on plan) with my eating, before I felt like working out. I still did my workouts, but I was dragging and fighting carb/sugar cravings like mad. I finally started to feel like my old (new) self yesterday.
You've done great with your weight loss, so far!
Are you still doing the same exercise you started with? If so, change it up. Do something different...start a beginner's running program like Couch to 5K, or take it outside, do some hills or hiking trails...ditch the elliptical for a while and do a bike or class or something different there. If your weight lifting routine hasn't changed, change out your exercises, and/or change your rep/set scheme. Changing these things will most likely get the fat burn cranked again. Doesn't matter how great your program or exercise is...if you never change it, your body eventually adapts to the work and then it doesn't have to work hard at all to do what used to burn a ton of calories. Give it a new challenge. You can go back to your faves later, in a month or two or three, and that will give you another boost.