Yeah, it's... VERY similar. Another thing people always say is they saw it on google as well. Even then, you should still mention where you got the inspiration from because that's still copying. If your "younger sister" is going to get you in trouble by asking you to add stuff, maybe ask her where she's getting the ideas from, just say no, or tell her to make her own oc/ account.
It doesn't make sense and seems all too convenient to say you got it off google or your sister told you to add stuff. Just change it and don't make excuses. It only looks worse for you Σ(=°ω°=;ノ)ノ
I’m very sorry about this 。・°°・(＞_＜)・° my sister is going to have a good talking to (^_^) ever since I noticed she was getting all these “ideas” from you, I’ve been trying to change my oc completely. Again, I’m very sorry about her.