I have never heard of ankle symptoms with ITP. I would guess that it is something else unrelated. Getting out of breath while walking to class is also not a direct ITP symptom. That said, many people with ITP end up with anemia as well as a result of blood loss. If your counts dip down on occasion, it is possible that you have had more menstrual blood loss than you realize, and may be anemic. Anemia definitely causes shortness of breath, so you should have your doctor check your iron levels.
Following up with a hematologist is a good idea. They can monitor your platelets and determine if you require any treatment. As long as your platelets are above 30k, you should be fine with just checking in with lab work periodically and not need any additional treatment.
This site has lots of great information for people with ITP and you can read about what symptoms come along with ITP. Reading about something makes it a lot less scary. If you are really having trouble with breathlessness, you can always go to your regular doctor to ask about your iron levels if you don't want to wait to see the hematologist. Good luck!