Heidi, Pat is correct, your vet is relying on you to keep her updated on Ginger's progress.
I just want to caution (not scare) you to be exceptionally keen on observing Ginger at this point. Because your vet suspects hemobart, it's important for you to know that this could take up to 4 months for her to make a complete recovery. During this recovery stage, it is paramount that you observe her carefully for any signs that treatment may not be working. Your vet wants to monitor her lymph nodes in the event she may yet need to test further for some other immunosuppressive problem. Assuming she hasn't truly ruled much out other than hemobart, she is keeping those differentials in the back of her mind as she follows the treatment plan.
The most observant thing you can do is monitor her mucous membranes on a daily basis. Ideally, they should be moist and a healthy pink color. Right now, they probably appear white or very pale, which would be normal under the circumstances, but what you want to see is her improving with pink gums each day from here on in. Another thing you want to monitor is her exercise tolerance, as in weakness. If she is lethargic or appears to be extremely weak, contact your vet immediately and notify her of it at once. While her normal daily routine has probably been adjusted and you'll find her not interested in activity or exercise or interested in playtime, etc, you should be seeing progress very soon. She should become stronger and more interested in her normal activities. Also keep a close eye on her food and water intake, especially during medication treatment. You don't want to risk dehydration, so ensure she is eating sufficiently, is drinking good amounts daily and has normal urine/bowel functions.
If at any time she appears not to tolerate her medications at any point, notify your vet at once. Sometimes vomiting can occur with doxycycline, and while it's generally mild and will subside shortly thereafter, if she happens to vomit more than once, notify your vet. If she is tolerating them well, follow the doses exactly, and never miss a dose of any medication your vet has given you.
Another reason your vet may want to see Ginger next week could be to monitor the CBC....anytime prednisone is given, the WBC needs to be monitored, this is a precautionary measure.
Hang in there.............Traci