Firstly good on u for trying to lose the weight, I need to lose a similar amount to u (am currently 112kg) and it is hard make a lifestyle change.
And also great your partner is supportive of your efforts !
I'm not sure why u are having troubles but try to only weigh yourself once a week as sometimes for a few days u will stall and then later that week all of a sudden seem to drop that kilo or half kilo !
I'm not sure why, but this is my experience, healthy fat foods such as avocado, raw nuts etc seem to actually help with the weight loss.
Im also on a meal replacement diet using ISOWHEY its fantastic, and add raw almonds, linseed, sunflowers seeds (about a tablespoon of each) and some frozen blue berries to my shake n out in blender, its beautiful, very filling, and has those good fats that assist in the weight loss
I lost 13kgs at the end of 2009 on Isowhey, it works ! I am the one who fell off the wagon in 2010 and went back to my old habits
Good luck to u, please dont get frustrated and give up. I'm sure by the sounds of what u are doing u will be successful