Firstly Good on you for putting all your hard work in and making the team, that is a big achievement and you should be VERY PROUD! Well done!
Now having been in similar situation myself with my own father, my dad has never really cared about me he has come to some comps and he did the exact same thing, to top it off when I moved out of home my dad started a photography buissness he was asked to photograph competitors in a 75cm jumping class, I competetd on my favourite little 4yo gelding my dad took photos of everyone else in the class except me his own flesh and blood.
He has been to some things equestrian and he does the same sits in the car or does not pay attention to me. I got very depressed about it. I joined a local SJ club which I do freshman's at, I started to talk to a few competitor's and quite a few live in the local area! And alot of them go to the same shows! I started to make some great friendships with in the club and now when I go to my shows I mett up with them I am invited to there trucks I have even been offered spots on trucks for myself and my horses! I have a lot of support offered and they are a great pick me up after a bad round! After meeting these lovely people I have never felt as disapointed about my dad not being there! And as they remind me it is not about him it is about you, it's your life and you live and compete in what you want to do!
Sorry if I turned it into a topic about me but just go out there and introduce yourself, you should click easily with people as you have the same interest and you can also tape or send pictures to your dad of yourself riding! Just go out and be the best you can be, it is all about you!