For a while my parents denied that I was transgender. The other day, my mom sat down with me and had a long talk about how she's come to terms with it and is now okay with me transitioning. It took such a long time for this day to come but I'm so glad that it's here. They haven't switched over to he/him pronouns or my new name yet, but I'm too happy with how far they've come to care. I just wish they came around sooner so I wouldn't have to do this on my own. I'm leaving for college in a couple of weeks all the way on the other side of the state, so I have to find out my options for starting HRT there. My college is LGBT friendly, so I can get help from the LGBT center but it's still stressful to think about because I'm barely even an adult. The only thing I have left to do is come out to my relatives, but I might end up putting that off until it's too difficult to hide oops.
It's best to come out when you feel comfortable. But don't deny yourself. They should know too. I'm sure your a great person, and your cousins will see that, even if your trans.
Awesome! Definitely suggest getting in touch with that lgbt center you were mentioning.. maybe try poking around the internet for places in your area as well. As Jeffreycominout said, you should come out to your relatives when you feel comfortable. Just remember that they're people as well and they would probably take it a little better if they knew sooner rather than later. In any case, best of luck to you! (*hug*)