As for not breastfeeding her for a week, it should only be a day or two of crying, before she realizes that she is going to have to wait. It will be hard. I weaned my daughter at your child's age and it was not fun. Some suggestions I have are:
Since you are co-sleeping face the other way. Hold her close to your body and against your chest and gently tell her, "No, booboo (or whatever you call it at your house) today, you can have some later." I had to do this with both of my children when I was weaning as they co-slept too. My husband and I just kept soothing our children and telling them that we loved them. IT WAS traumatic, but we did survive.
When I had to wean my daughter I gave her a pacifier. It wasn't the ideal situation or choice, but I was at a loss as to what to do. She hadn't had one since 9 months old. That was definitely a big help. I also gave my children a lot of yogurt, cheese and lean meats when I was weaning so that they got enough protein and calcium since they were not really into milk in a cup. I hope this helps,I know you are not weaning, but you might have to have it in your mind that you are.
Unfortunately, my friend had to do this with her daughter for a medical procedure and her daughter ended up weaning. Just a thought, prepare yourself for everything:) I wish you the best with your test tomorrow and I hope your week isn't too bad.