Ah sorry for you Lilliesmum. I too have masses of cousins so get where you are coming from. One of my parents was one of 11 the other one of 4. Needless to say there are first cousins who I’m on nodding terms with, and some I’d pass in the street without knowing. So I don’t think you should feel bad at all.
It’s impossible unless your parents families stuck together how could you expect to be close. I think you did your share caring about your own mum and dad, it was up to anyone else after that and not to pressure you. You mustn’t feel bad.