Keoh:
Since the treatments can be quite harsh and most have side effects, doctors usually do not treat unless counts fall below 20k. Monitoring is the best move right now. Counts of 50k+ is considered to be a safe count for most activities. GP's may not be all that familiar with ITP, so they become concerned at higher counts than a hematologist would.
Diet changes do not always help with ITP, but some people have noticed improvement by eliminating some foods. No one thing works for everyone, so you have to try different things to see if anything helps. It can take quite a while to see results, but even if it improves your general health, it is worth it.
Symptoms of ITP usually revolve around bleeding....bruises, petechiae, blood blisters, etc., although some people do report being tired. Most do not have symptoms unless counts get below 30k; some do not have symptoms until below 10k.