But you can learn about and respect the Jewish heritage of both your father and the Catholic Church.
The Catholic Church officially teaches:
When she delves into her own mystery, the Church, the People of God in the New Covenant, discovers her link with the Jewish People, "the first to hear the Word of God.
The Jewish faith, unlike other non-Christian religions, is already a response to God's revelation in the Old Covenant.
To the Jews "belong the sonship, the glory, the covenants, the giving of the law, the worship, and the promises; to them belong the patriarchs, and of their race, according to the flesh, is the Christ"; "for the gifts and the call of God are irrevocable."
Neither all Jews indiscriminately at that time, nor Jews today, can be charged with the crimes committed during the Passion of Jesus Christ. The Jews should not be spoken of as rejected or accursed as if this followed from Holy Scripture.
For more information, see the Catechism of the Catholic Church, sections 597 and 839:
http://www.usccb.org/catechism/text/pt1sect2chpt2art4p2.shtml#597
http://www.usccb.org/catechism/text/pt1sect2chpt3art9p3.shtml#839
I'm Jewish. I'll tell you to go where your heart leads you. Do you "feel" more Jewish? Do you believe that Jesus is the savior? If you do then you're not- and can't be- Jewish. I personally would never want to be anything but Jewish, but I grew up always knowing that I was a Jew even though my dad was Catholic. Of course, in Judaism you are what your mom is so I AM Jewish by birth. If you don't know that much about Judaism get a few books and start studying and maybe go to a few Shabbat services (does your dad go? Go with him) Talk to a rabbi about what you're thinking- they can be a huge help, but won't make it easy for you because they want you to be really, really sure before allowing you to start conversion classes. Once you are a Jew- you're a Jew for life- it's serious business!!!! And it's not the easiest religion to be a member of! But, if you have that Jewish heart, you'll be fine! Good Luck and mazel tov!!!
I believe strongly in the Resurrection of Christ and in the Real Presence of the Eucharist, so I can't in good faith encourage you to convert to Judaism.