Hi there and thanks so much for posting this interesting question. Feel free to post this question in the bulimia forum as well.
Regarding your question as you may know bulimia it is a really serious condition and needs to be treated so I hope you are under supervision. I am going to suggest you few starting points so you can start on the rigth track but please ask a doctor and make sure we are all on your winning team. Your symptoms are normal and you need to get started by training endurance. So first go walking, you can get a heart rate monitor and make sure your heart stays in the aerobic range (220-age) then stay at 50%, very mild, if you feel you are running out of breath means your heart and muscles are not condition for that given intensity and you may fall into the anaerobic range (without oxygen) where you need to stop immediately. So I would suggest ten minutes in the treadmill at very mild walk or fast walk as long as you don't run out of your breath. Then you need to condition your muscles at the same time by increasing progressively your strength. So get bottles of water and raise your arms fifteen times then rest for 30 seconds then raise your bottles over head 15 times and rest for 30 seconds. You want to train a lot of repetitions with very low resistance. Then finish with some balance exercise like from a standing position raise one leg and hold that position for 20 seconds then change.
Then finish with Meditation for a calmer Mind and more focused brain. Anxiety and stress is a real killer and meditation can help you. Just sit down in a quiet place and breathe deeply focusing in your breathing, do it 100 times
I hope this helps and make sure you consult your doctor before you engage into any form of physical activity
Thanks so much
Thank you very much Michael!