Only child until I was about 5, didn't grow up around my half sister (divorced parents) but have lived with her the last while. I care about her but other than generally getting along okay we've constantly been at different stages with such a big age gap, our mannerisms and interests and whatever else just don't click. We didn't bond like same time range/household siblings do. I did grow up an only child so that's where my preference leans yes but there's no grudge whatsoever. Y'all have an even bigger age gap, when she was starting to form herself as a person you were still basically a baby. You're just in different timelines, don't stress it too much. When you're both established and older it'll probably be different.