it is definitely necessary for you to add your name if you want

since the house was bought before the marriage, it is not community property (suppose you are in a community property state). Thus, I don't think you can get a piece of it. You even need to provide evidence to show that you are paying 1/3 of the mortgage every month if you want to be fair and get the portion you have paid.

The process to add your name to the title should be really easy. If he doesn't want to add your name, it only means he is not ready to share his personal property with you yet.