Flying with very low platelets is indeed risky and that's a pretty long flight. The subject has come up here before (for example, see
this post about flying). You should definitely ask your doctor, who may very well recommend that you rule it out until your counts are higher. As much as it would make you feel normal to fly, you may not be "normal enough" yet.
This is the type of question that doctors may be able to answer over the phone or by email, since you don't need an exam, just advice and a risk assessment. Please let us know what the doctor tells you, since other patients have had the same concern.