Bf’s sister didn’t tag me at her bday dinner :(

Hey guys! So me (24F) and my bf (29M) have been dating for a little over a year. He is very close with his family (and still lives at home) and my family lives hours away so we spend a lot of time at his house with his family. His sister does not live there but I think we have a good relationship thus far and have spent a lot of time together. We text here and there & she is always very nice to me. She invited me to her birthday dinner yesterday so of course I went! It was me, my bf, his sister (bday girl), her husband, one of their friends & niece. We had a good time. However, when I got home I saw their friend repost a story that she tagged everyone in except me. :( I felt a bit sad and started overthinking about the post. It was like I wasn’t even there. We do not follow each other on social media but after I saw the post I requested to follow her. I’m wondering if she didn’t tag me because we don’t follow each other or bc of something else? (Does she not think me and her brother are gonna last? Or does her brother not want her to tag me?) Idk I have a lot of questions now but idk if I should just let it go or talk to my bf about it. She also hasn’t accepted my friend request yet :/

TL;DR: Me and my bf’s sister get along great, but don’t follow each other on social media. She tagged everyone at her birthday dinner except for me :(