I'm saying I'm an only child but I'm not
That seems very odd. Why would you lie about being an only child?
In my family, I'm different from everyone else.
I understand that you feel unique, but that doesn't mean you should lie about being an only child as your other siblings may feel hurt if they found out you have been lying. Try to be more proud of your siblings and see that they have unique characteristics too just like you.
There you go pointing reality and facts at me again.
I do not think that I am trying to annoy you pointing out the facts, but I feel like you shouldn't disregard them as living in a constant lie that you tell people can lead to a very harmful outcome in the end like breakups and legal issues that you may face in the future. I do hope you consider everything you are saying and see the repercussions of lying so that you at least minimize telling them.