Make sure you let her know what you just said here about the inches and gaining muscle mass. That might sway her a little.
I did do a lot of walking to help lose the weight, but not enough to make a difference with muscle.
Also, what kicked it up for me was, shake for breakfast, lunch and then just meat and veggies for dinner. The Adkins shakes are very filling and taste great. Also, the GNC 100% whey protein is very very good too and is even better than the Adkins. Those you make yourself. I use double the powder and milk rather than water and that makes them taste great.
And most important THINK POSITIVE YOU CAN DO IT!!!!!!!!!!!!!!
Listen, you can forget the nervousness, I am being nervous for you right now, LOL!! This is exactly how it was for me near my date. Crazy with nerves, but it will be ok. Just KNOW that it will be ok and it wil be!