Anyone else not have a good relationship with their sister in law? Advice?

So I've been married to my husband for 3 years and I just can't seem to create a relationship with his sister. Nothing has ever happened between us, and she's never done or said anything deliberately mean (to my knowledge) towards me. She's just not the friendliest to me. I try to have conversations with her and she'll barely respond or if I ask her questions about her life and how she's doing, she'll answer briefly and that's it. Never asks about me or how I'm doing. I honestly feel like if I never initiated conversation with her then she'd only ever say "hi" and "bye" to me when we all get together. I'm trying to have a better relationship with her it's just so hard. I've talked to my husband about it and he basically just says that's just her personality and the way she is and it's not necessarily me. Even if that is the case, I just end up feeling awful and like she doesn't like me. I feel like she talks more towards others when we get together but not me. And I know this sounds petty and dumb, but she will "like" my other sister in laws posts on IG and such constantly. But whenever it's mine she doesn't. Even the things that include my husband (her brother) she doesn't like. And I know that's something dumb and small, but it makes me feel like it is just personal. She's 20 and I'm 26 btw. I would talk to her about it but I feel like we have zero relationship as it is so it would be super awkward to address it with her. Anyways, so what do you ladies do about your relationships with your sister in laws? Any advice?