You should verify who the owner is currently
If you have a contracto de compra-venta only then the land is still owned by the origional owner, there are things you must consider in this case.
1) The contract should identify the lot i.e. solares by parcela, manzanna and lot# if it is in an urbanization zone, this identification should be on the contract, next you should go to your local Tribunal de terras and as one of the assistance to look up the lot for you (a tip is expected when they are done). If it is not found that is an indication that it might have never be desilinda and as suce the planners of the ubanization zone might have changed the designation for the lot since your contract was written. In addition to being able to verify the lot, I think the tribunal de terras should also be able to identify the owner of the lot, make sure this is the same as the person you bought the land from. If you have a lot that in general is designated as a "Resto de la Parcela" then chances are the people in the "Tribunal de Terras" will not want to be bothered with searching for it, (they might have 20 or 30 or more for a single parcela).
My personal opinion, get another laywer to process the contract to a title. The more you wait, the more problems you will have, in general it is typical for people to be duped into beleving the transaction has completed when only a contracto de compra venta exists.
Taxes might accrue over those years also, some one else I am sure will clarify this.
-Lee