If you never filed paperwork with the county assessor to legally change the deed to your name, then you don't own the house.
Whether or not you can still transfer it to your name depends what kind of written contracts you have which you can verify.
In most parts of the world, paperwork transferring ownership of real estate must be notarized. So even if you have a written contract of some kind, it might be null & void without a notary stamp.
Its also possible that you won't be able to claim ownership of the home, but might have a claim against the estate. For example if you had a rent-to-own contract which stated that a certain portion of your monthly payment was to be set aside toward the purchase, you might be able to demand a refund (from the estate) for that portion which was supposed to go toward purchasing the home.
In any case, you need a lawyer as soon as possible. It shouldn't' cost too much to have an attorney do a basic review of whatever contracts or written agreements you have, and tell you what your options are. If you actually need the attorney to file a lawsuit on your behalf that would cost more.