I get the fear of the unknown, but really this is all about trial and error and once you've trialled something for a max of 3 months, you know how it is going to go... it's unlikely to change unless you change something.
You don't really need your GP's approval to make this change. If I were you, I'd just do it and then tell her about it at your next review. Then you can also tell her how it's going. If it has solved things or not. Which means your next review will actually move things on faster because perhaps, if it doesn't help, you'll be onto the next thing.
Otherwise you are just delaying feeling better because you won't try changing anything until then and will then have to go away and trial it before you know if it helped...