you may not have had a fixed term written lease but by virtue of you being in the premises with rent abated until you "got onto your feet" shows you did in fact have a lease. A lease does not have to be written nor does it have to be for a fixed period of time. What many people call a rental agreement is considered a lease.
while you may have insisted your original agreement was to be able to live there with no rent due, since you did not have a fixed term lease, the landlord has the right to alter the terms of the lease with proper notice. That means she can change your rent from $0 to anything she chooses as long as you are given a proper amount of time in the notice.
I have sympathy for your situation but in the end, whether you misunderstood what was offered or the landlord changed what they were willing to accept, the fact remains, you are a tenant and the landlord has a right to demand rent payments. Should you fail to pay those demands, your tenancy can be terminated and you can be required to leave the premises.

