Am I Jewish?

Hello Rabbi, I’m from Honduras, 23 years old, my grandparents had sephardic roots, their family names were David-Perez Castro. They got married when there was not a jewish community in our country but they signed a Ketubah, confirming their willing to live according the religion of Moises and Israel. The ceremony was performed by a sephardic jew his familiy name Salomon, he had knowledge about how to perform a jewish wedding but the Ketubah was not issued by the local community since on those times there were only 2 sephardic families in Honduras. My question is: Am I jewish? Even when they signed a Ketubah? as mentioned was not issued by a local community or by a recognized Rabbi? Also we have kept our family tree which shows our ancestor until 1750 and they kept the family name (David) by leaving Portugal. Thanks in advance.

As you probably know, your Judaism is determined by your mother, her mother, her mother etc. etc. You didn't give enough information to answer that question but that is the simple rule, so check it out.