I asked my mum if she'd be able to alter it for me. I told her I'd be willing to part with the waist ties if I had to but would rather not have to. It sat in her pile of things to do for quite some time and finally today, she had some extra time to alter my skirt! I came home to a wonderful surprise. My mum had taken the elastic band out and added a few inches to my skirt and it fits perfectly! She didn't even have to use the waist ties! Well actually, I should say she didn't need to use all of them XD She took about 2 inches of the bottom of both ties and the refinished them. If she hadn't told me she had used them, I never would have noticed!
Now I just need to get some pieces to coordinate it with!