I'm an independent contractor that works in a smaller group of four people. Our lead, his wife, myself and one other women named Sara. Our lead decided that we should all go out to celebrate his wife and my birthday together at a happy house. So we get to happy hour and Sara shows up with a gift for our bosses wife. I don't care that she didn't get me a gift, but we were there celebrating both of our birthdays so it felt weird and I didn't bring his wife a gift. So now I feel horrible. I make like no money so I don't have any extra money to spend on gifts. Am I wrong to have not gotten a gift? Was it weird Sara would bring a gift for just her? Or am I just overthinking this?

No, there was no reason for gifts, and the other person was just sucking up to the boss by buying a gift and being rude for not getting you something.

Just forget it, as a jerk, if you think more than one minute on it you over thought it

You are underthinking this because Sara was brown nosing and maybe you watch your back and CYOA.