The Belgium consulate is the best place to get an answer about passport turn around. Also it never hurts to ask again if any combination of documents will be accepted for renewal stateside, i.e. expired pp+birth certificate.
I agree with my colleagues, as this is not a US immigration law question.
If you don't have FL ID, I suspect that you are not in the US lawfully and may need to have the Belgium Consul issue you a one-way-passport.
PROFESSOR OF IMMIGRATION LAW for over 10 years -- This blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship.
Your question is for the Belguim Consulate and not for a USA immigration attorney. Most consulates in the USA will not renew your passport unless you can show that you are in the USA legally.