Doesn’t feel like family

I don’t really have the strongest relationship with my family members. They never really reached out to me as a child to have a relationship with me so now at 20, things are pretty weird around them. I don’t feel like this is “family”. I don’t feel like I’m wanted or that I fit in. Last year my cousin called me useless. How would she know? She doesn’t know me well enough. Anyway, they have an annual family camping trip. I’m 20 and this is my first year being invited. They invite over 50 people every year... and every year they have excluded me.. until now. My cousin had told me that everything was already planned and paid for. That same cousin is now saying that I owe her the money for my spot. It’s only $100, I have the money... but they should’ve told me before. I don’t understand how she pays for other peoples spots, but me, her “family” has to pay. Like when she paid for her sons girlfriends plane ticket before and said she didn’t have to pay her back.. but sure, you want my $100. Just like when they planned a family trip to Florida two years ago and invited me but then said I couldn’t go because her friends had taken the last available spots. Anyway, I’m of course going to give her the money. I’m going to go and try to have a good time 😊 I love camping and the outdoors! Just thought this was weird but maybe I’m overthinking it!